Whisky Science

Sugars in whisky

noreply@blogger.com (Teemu Strengell) — Sat, 10 Dec 2016 17:22:00 +0000

There are small amounts of sugar in all whiskies. Scottish whiskies have some sugars dissolved from the oak cask and often some from optional caramel colouring (E150a). Total amount of sugars is quite low, usually well below 1 g/l, but in certain cases it is quite possible to reach a few grams per liter. The sweet aromas of whisky matured in refill bourbon or new oak casks mostly come from sweet aromatic vanillin and fruity esters, not from the sugars. However, sugars can have a significant role in the case of casks previously used for sweet wine or sweetened spirit.

Typical composition of a liquid E150a colouring

Sugar gets to whisky from the oak cask used in maturation and its possible previous contents, especially sweet wine, and often from optional caramel colouring. New make spirit does not contain significant amounts of any sugars and it is not legal to add sweeteners to Scottish whisky, Irish whisky or bourbon, unlike to most rums, other American whiskies, Canadian whiskies, cognac, armagnac, vodka and so on. However, caramel colouring is an allowed additive in Scotch whisky. The E150a colouring used in whiskies consists of mostly of water (30-50%), carbohydrates (50-70%) and ash (0-4%), depending on the manufacturer. The colour comes mostly from furans and furfurals, mainly 5-hydroxymethylfurfural (5-HMF). The carbohydrate composition varies a lot, but usually the amount of simple sugars (mono- and disaccharides) is about 10-20% of the total volume and about 20-40% of the total carbohydrates. Caramel colouring as such is not sweet but rather bitter, although it probably enchances the perception of vanillin and some other sweet notes while supressing some sulphury notes. The amount of caramel added to whisky is usually well below 1 g/l, but there is no legal upper limit, although 2g/l of E150a (0,2-0,4 g/l simple sugars) would render the whisky very dark. In one independent study the highest caramel solids amount found in a Scotch whisky was 0.97-1.10 g/l (simple sugars ~0.2-0.4 g/l) depending on the analysis method (I suspect L*******g, but no names) and the average amount was 0.278 g/l caramel (from 0.01 to 1.10 g/l). According to Valaer in 1940 there was a legal maximum of one pint of liquid caramel per barrel of whisky permitted by the British Customs and Excise Regulations (0.15% or about 1.5 g/l).

Caramel content of various whiskies (Boscolo et al 2002)

Another source of sugars in whisky is wood. Oak is composed of three main macromolecules; cellulose is a long-chain D-glucose-fiber. Hemicellulose is a mesh-like branched chain of 5-carbon sugars (xylose, arabinose, galactose, ribose, rhamnose) and glucose. Lignin is a complex matrix of polypropane and polyphenols. Cellulose breaks down very slowly in alcohol-water solution extracting very small amounts of glucose to whisky. Most sugars extracted from the cask come from hemicellulose, hence most of them are 5-carbon sugars. Arabinose, xylose and rhamnose taste about half as sweet as glucose, where as fructose is almost twice as sweet compared to glucose.

About 100 mg/l of solids (including sugars) is extracted from new charred oak casks during the first year of bourbon maturation and after 1-3 years typically significantly less and only as little as 4 mg/l/year extraction has been reported from old refill casks used for example for cognac (or Scotch) maturation. A toasted cask extracts considerably more sugars compared to a charred cask, but typically about 150-250 mg/l/year is reached for the first year(s) of maturation. For comparison, a 40 years old brandy matured in a toasted oak cask had 2 g/l sugars (averaging 50 mg/l/year), while a 30 years old cognac (probably mostly matured in a refill casks) had only 0.5 g/l (17 mg/l/year).

Sugars dissolve in water better than in ethanol, so for example 55% ethanol-water solution can extract almost two times more sugars from the wood compared to 70% abv solution. The difference between 40% abv and 15% abv seems to be just about significant, so the alcohol strength is probably important only for high proof spirits. High entry proof is likely to significantly diminish the sugar extraction. Toasting and especially charring of the oak lowers the amount of extractable sugars, converting them to for example furfurals ("caramel"). On the other hand, charring contributes to sweetness by increasing the formation, extraction and perception of other sweet-tasting compounds, especially vanillin.

Analysis of different spirits by GC-MS (Savchuk 2001) Note the high levels of vanillin from new charred casks.

Probably the most important factor considering the amount of sugars in Scotch is the previous content of the cask. The most usual type of cask, the ex-bourbon cask would impart minimal amounts of sugars, often well under 50 mg/l/year and overall well below 1 g/l even during a long maturation, usually in the range of few hundreds of milligrams per liter. The charred American oak cask used for bourbon is quite low on sugars to start with and the bourbon will extract a major part of the available sugars. A toasted cask previously used for cognac, armagnac, brandy of other non-sugared spirit could extract slightly more, but most likely still not over amounts 1 g/l during refill maturation.

Venezuelan rum, 40 g/l sugars

Rum can, and often does, contain added sugar or other sweeteners. Most sweetened rums are sugared at the bottling phase, but sometimes sugar (or molasses, cane juice, fruit etc) has been added already into the cask and some of that sugar is bound to get into a ex-rum refill Scotch. Up to 40 g/l sugar contents are commonly reported in rum (100 g/l in spiced rums), but the amount of sugar added directly to cask is likely to be in the range of 5-20 g/l.

Pedro Ximenez sherry,
470 g/l sugars

Significant amounts of sugar can be extracted from a sweet wine cask. Sherry is by far the most used ex-wine cask in the Scottish whisky industry. Most sherries, such as fino, manzanilla, amontillado, palo cortado and most olorosos, are dry wines (0-5 g/l sugars) and add only little sugars to the cask, some might even extract more than impart. Most sweet blended sherries (cream, dulce, sweet olorosos) are often blended with sweet must prior to bottling, not in maturation casks. The sweetness perceived in the olorosos often comes from high amounts of glycerol, not as much from sugars. A notable exception is Pedro Ximenez wine, which nowadays is vinified almost exclusively in Montilla-Moriles. It is a sweet wine produced from late harvested dried PX grapes and it typically contains by law over 212 g/l sugars. It is quite sweet even compared to other sweet wines, such as port (usually 100-150 g/l), Sauternes (100-200 g/l), Tokaji (60-500 g/l) or icewine (180-320 g/l).

The Scotch whisky industry has preferred sweet sherries for seasoning of their whisky casks from the 19th century and while most modern sherries are quite dry, most ex-sherry whisky casks were used for (or seasoned with) sweet sherries. In the 1800s and the early 1900s sweet(ened) sherries were imported to Britain in shipping casks. Britain was a major importer of sherry and emptied shipping casks were often used for maturation of Scotch whisky. By the late 19th century sherry casks were used extensively in Scotland and the first attempts to rejuvenate or season used casks were made in the 1890s. After the sherry casks were used for Scotch whisky maturation, they were seasoned with sweet sherry or paxarette, sometimes using pressure to soak the wood with the wine. By the early 20th century the use of sherry casks was quite wide spread, for example in the late 1920s a big whisky blender Johnnie Walker matured all of their whiskies in sherry casks or sherry-treated casks.

Aberlour 18yo
sugars <2 g/l

Shipping casks were mostly Spanish coopered lightly toasted American oak (Quercus alba) butts or puncheons (often called bocoyes in Spain). In 1972 Manuel González Gordon stated that "in recent years some Spanish oak has been used, due principally to the difficulties of importing American timber, but its greater density and hardness and lower porosity make it less suitable than the American wood". In the 19th century and the early 20th century they were often used for fermentation prior to shipping. Oak influence was not that detrimental for sherry during fermentation period and the fermentation process was believed to extract some of the excess tannins and bitterness from the wood prior the use in a solera or shipping.

The fermentation phase added plenty of sugars to the oak. For example, a typical 1980s (arguably Spanish oak, but at least Spanish coopered oak) shipping cask previously used for fermentation extracted 2.25 g/l sugars to whisky during only 6 years of maturation (375 mg/l/year). On the other hand an American ammonia-treated cask without a previous fermentation use would extract 770 mg/l (154 mg/l/year) sugars from a fino-seasoned cask and even less 655 mg/l (133g/l/year) from a similar oloroso cask. According to the table below, the previous use as a fermentation cask is very significant in the terms of sugar extraction.

JM Philp 1989

Ardbeg Dark Cove
4 g/l sugars

The most important factor considering the sugar extraction is probably the sweetest liquid to occupy the cask previously. According to Manuel González Gordon "large solera butts which have been used for years in a solera sometimes gain up to 25 kilos" in weight. In case of fermenting must or sweet wine, the refill cask can extract at least up to about 400 mg/l/year sugars. A typical sherry treatment used for Scotch whisky casks used in the 1890-1970s was made with about 35 litres of paxarette or sweet sherry per hogshead, but even with a relatively high pressure only a small part of the wine was absorbed into the cask. If we presume that as much as 5 litres of paxarette (375 g/l sugars) was absorbed into a hogshead and half of its sugars (just a figure from top of my hat) was extracted to the whisky, it would have resulted into 1875 g/ 220 litres = about 4.3 g/l of sugars, with a hypothetical gram or two from the cask itself could theoretically bring the sugar content up to 6 g/l during a very long maturation, say an average of 300 mg/l/year for 20 years. If were take a purely fictional solera butt used for an extremely sweet PX-wine (400 g/l) with 25 kg of PX wine absorbed into the cask and then used for whisky maturation, it could mean 10 kg of sugars in the cask and with a purely fictional extraction of about half of the sugars would result roughly to the amount of 9 g/l sugars into the whisky in an extreme(ly long) maturation from an extreme cask. It is probably safe to say that most spirits with over 10 g/l sugars contain additives and most spirits with over 2 g/l were matured in ex-sweet wine casks. Nowadays the sherry casks used in the whisky maturation are no longer used for fermentation or exposed to high-pressure paxarette/PX-treatment. The seasoning sherries are probably mostly medium oloroso/raya sherries with a sugar content in the range of 0-100 g/l, so a typical sugar extraction from that kind of cask could be in the range of 100-300 mg/l/year and diminishing through maturation, resulting to a maximum of a few g/l sugars into a modern whisky even during decades in a cask.

REFERENCES AND FURTHER READING:
Alañón ME et al. Monosaccharide anhydrides, new markers of toasted oak wood used for ageing wines and distillates. Food Chem 2010;119;505-512
Blanco Gomis D et al. Evolution of sugars in cider brandy aged in oak barrels, a contribution to its characterization. J Agric Food Chem 2003;51;923-926
Boscolo M et al. Spectrophotometric determination of caramel content in spirits aged in oak casks. J AOAC Int 2002;85(3);744-750
Boudet AM et al. Biochemistry and molecular biology of lignification. New Phytol 199;129;203-236
Clyne J et al. The effect of cask charring on Scotch whisky maturation. Int J Food Sci Tech 1993;28;69-81
González Gordon M, Sherry. Cassell Ltd 1972
Haldane FF. Casks; their manufacture and treatment. J Inst Brew 1906;12(7);688-711
Hills, P. Appreciating whisky. Collins 2000
Kansallisarkisto, Helsinki. http://www.arkisto.fi/en/the-national-archives-service/arkistolaitoksen-vaiheet-2
Liebmann AJ & Rosenblatt M. Changes in whisky while maturing. Ind Eng Chem 1943;35(9);994-1002
Martínez Montero C. Estudio de parámetros alternativos como indicatores del envejecimiento y de la calidad del brandy de Jerez. Thesis, Universidad de Cádiz, 2006
Martínez Montero C et al. Sugar contents of brandy de Jerez during aging. J Agric Food Chem 2005;53;1058-1064

Mosedale, JR. Effects of oak wood on the maturation of alcoholic beverages with particular reference to whisky. Forestry 1995; 68; 3; 203-230
Mosedale JR & Puech JL. Wood maturation of distilled beverages. Trends Food Sci Tech 1998;9;95-101

Piggott JR et al. Effects on scotch whisky composition and flavour of maturation in oak casks with varying histories. Int J Food Sci Tech 1993;28;303-318
Piggott, JR et al(ed). The Science and technology of whiskies. Longman 1989

Read J. Sherry and the sherry bodegas. Sotheby's 1988
Savchuk SA et al. Application of Chromatography and Spectometry to the Authentication of Alcoholic Beverages. J Anal Chem 2001;56(3);246-264
Tolman LM & Trescot TC. A study of the methods for the determination of esters, aldehydes and furfural in whisky. J Am Chem Soc 1906;28(11);1619-1630
Tsai PJ et al. Interactive role of color and antioxidant capacity in caramels. Food Res Int 2009;42;380-386
Valaer P & Frazier WH. Changes in whisky stored for four years. Ind Eng Chem 1936;Jan;92-105
Valaer P. Scotch whisky. Ind Eng Chem 1940;32(7);935-943
Valaer P. Foreign and domestic Rum. Ind Eng Chem 1937;Sep;988-1001
Williams JF. Rapid determination of alcohol in distilled spirits and of color in whisky. Ind Eng Chem 1926;Aug;841-843

Scottish pot still variations

noreply@blogger.com (Teemu Strengell) — Thu, 24 Sep 2015 14:05:00 +0000

Scottish whisky distilleries accommodate a variety of different pot stills. Volumes vary from the 30963 litre wash still of Glenkinchie to the 2179 litre spirit still of Edradour (artisanal sma' stills excluded) and height from a couple of metres to the 8m tall Glenmorangie stills. Most are roughly onion shaped, but there are significant differences from the tear-shaped Bunnahabhain and Lagavulin to the slender Glenmorangie and Bruichladdich stills. Many stills have a wide bottom and a constricted neck, while several have a bulbous boil ball (aka reflux ball, Milton/Balvenie ball or bulge) in the middle section. Overall, the Scots are quite traditional with their stills, but occasional purifiers, still-neck coolers and a variety of condensers are still used. Most have converted to steam coil heating, while some still apply direct fire to the stills. In the history there has been a greater variety of stills, sadly more often to avoid taxation or speed up the distillation than to improve the distillate. In the 20th century the influence of North American distilling companies brought some interesting experiments with the reflux or Lomond stills, but the traditional pot still prevails in Scotland.

Tall Glenmorangie stills (photo: BBC)

Early distilling stills were usually quite small and direct-fired. There was not much of a commercial distilling until the 17th century. From 1644 the spirits in the United Kingdom were taxed by the gallon of proof spirit and the taxation did not really affect the distillation methods. Anyway, most distillers did not pay the taxes, as many distillers were just farmers saving the surplus grain for the winter as a spirit. In 1725 the malt tax was raised in Scotland to the English level. This caused riots and decreases in ale drinking, leading people to consume illegal spirits instead. In 1780 wine was taxed heavily and again the illegal distillers gained customers. A year later all private distilling was made illegal, though not to much effect in the Highlands. The use of mostly illicit stills affected the size of the stills used from the 18th century in the Highlands. They should be easy to transport or hide, so increasingly smaller stills were used as the Excise control became stricter in the late 18th century.

Sma' still (decoration at Glenlivet, photo by mrtattiehead)

Due to rapid increase in illicit distilling, the crown allowed to licence over 20 gallon (91 litres) stills in the Highland area in 1784. As this did not have much effect, the limit was raised to 40 gallons (182 l) and all spirit exports from the Highlands were prohibited to England in 1785. At the same time the spirit duty was calculated according to the size of the still and the stills were assumed to be used seven times a week. This led to the use of very shallow 'Millar' pan stills from the 1790's, especially in the Lowlands, where the Excise surveillance was effective at least to some extent. The Lowland still was claimed to operate in 3 minutes, providing significant tax benefits, but extremely coarse spirits. The pan still was wide and shallow, usually just a few inches inches deep and usually just about over the minimum legal capacity. Additional upwards expanding coils or pipes were introduced into the still to maximize the evaporation at the bottom and condensation at the top.

Millar shallow stills (Forbes, 1948)

Lowland still sure was fast, but offered minimal reflux, copper contact and virtually no chance to cut the spirit correctly. So the coarse Lowland spirit often had to be rectified, ie redistilled or spiced heavily. Since the crown could not catch most of the illegal distillers and lost huge revenues because of the legal Millar stills, they decided to prohibit all stills under 2000 gallons (9092 l) in 1814. This effectively stopped pan distilling in the Lowlands, improving the quality, but put legal quality Highland distilling under ground until 1823, when taxation was eased considerably. In fact the over 40 gallons stills were legalized in 1816, but this had not much effect on the Highland stills or their desire to go legal.

Conversion to steam heating
*previously used steam jackets
**spirit still converted 2001

Another major improvement in efficiency was the use of steam, first directly on the pot or via a steam jacket, but later by indirect heating by steam coils. Direct steam heating for distillation was first implemented by dye manufacturers in the late 18th century with good heat economy. The first distillery to use direct steam heating of wash was English Mesly distillery in 1801. Indirect heating by steam jacket was used in Irish Roscea distillery in 1818, but the Excise Board rejected it because of difficulties in estimating the still capacity. The Coffey stills were heated by steam, but the pot stills were mostly direct-fired up to the mid 20th century. It was until 1887 Glenmorangie was the first Scottish distillery to use steam heating. Auchentoshan had steam jacketed heaters from early 1900s, but the majority of distilleries converted to indirect steam as late as the 1950-60s. In continental Europe and Scandinavia the steam heating became more widely used, especially after Savalle's invention of steam regulator in 1857.

Steam coils inside a spirit still

There are still Scottish distilleries using direct-fired stills; Glenfiddich, Glenfarclas and Macallan use direct-firing for both wash and spirit stills, while Springbank, Glen Garioch and Tobermory use direct-fired wash stills. Direct firing provides more temperature fluctuation both in the still and the contents. High temperatures can lead to burning and excess formation of furfural (nutty,burnt) or sulphurous and vegetal notes, especially if there is lots of sediment (dead yeast, grains) in the wash. To prevent this burning, direct heated wash stills have been installed with rummagers, ie rotating chains to keep the solids moving at the bottom of the stills.

Early 19th century was the golden era for still experiments. The still heads were adjusted in many ways; there were soap trays and stirrers to minimize frothing, steam coats to enable more even distillation and most importantly several means to enhance the reflux with boil balls, cooling condensers, refridgerators, trays and series of boiling chambers, which probably eventually led to the birth of the continuous stills by Adam, Fournier, Blumenthal, Stein and Coffey.

Balvenie spirit still with a boil ball

A common way to increase reflux was to shape the stills so that the rising vapours were cooled or exposed to lower pressure and copper. This was easily done by adding bulbs or balls in the still head. They were and are still common in the Speyside. Boil balls could be one reason for the perceived fruity and light "Speyside"-style of spirit, since they probably increase copper contact, reflux and ester formation, while decreasing the heavy oily and sulphury notes.

Still head cooler at Dalmore

Water cooling of the still head was probably first tested in late 18th century, the first patent is by Pontiflex from 1798, but the first Scottish distilleries to commercially cool their still heads were Hazelburn (1837), Dalmore (1839), (Ben) Nevis (1878), Fettercairn (1890) and Littlemill (1931). They used different methods for this, as Hazelburn had basically a tube condenser installed at the top of the still, where the spirit passed through pipes, which were cooled by water circulating in the condenser unit. Dalmore simply had a water jacket around the still head. Nevis, an extension of the Ben Nevis distillery, probably used a water jacket similar to the one in Dalmore, although there have been (unconfirmed) claims of a Lomond style cooled plate systems inside of the still. Littlemill had an early version of the Lomond still combined with water jacket coolers outside the still.

Nevis (Barnard, 1887)
Purifiers in the front left row, still head-cooler in the back

Intermediate condensing vessels between the still head and the worm were proposed already in 1736 by John Payne. The distilled wash or spirit is condensed inside a water jacketed purifier situated in the swan neck of the still and the heavier stuff is returned into the pot making the spirit lighter and higher in alcohol. Cooled intermediate condensers (water cooled purifiers) are still used at Glen Grant, Glen Spey and Strathmill distilleries.

Glen Grant uses purifiers on all stills

Glenugie purifier

Uncooled purifiers (basically a pipe descending from the lyne arm back to the still) are used in Ardbeg, Glenlossie and Talisker.

Ardbeg purifier (photo by www.coolhunting.com)

After the distillate leaves the still and there is no turning back via reflux or purifier, the spirit must be cooled. The traditional cooling method is a worm tub, consisting of a pipe wound into a spiral and immersed into a cold water tub. German chemist Christian Ehrenfried Weigel invented a worm tub in which the the cooling water was circulated to keep it cold (the Liebig condenser). The tube condenser with multiple straight copper pipes inside a cooled shell instead of a single coiled one in a tub was invented in 1825 by William Grimble. The shell and tube condenser provides more copper contact and is much more durable. A dozen Scottish distilleries still use worm tubs.

Disused worm at Auchentoshan

The Lomond still is a pot still with several horizontal (often perforated) plates inside the still neck. They became more popular in the Northern America and several bourbon and Canadian whisky distillers continue to use reflux stills, as they are often called over there.

Lomond stills at Glenburgie

The first commercial reflux still in Scotland was installed in Littlemill distillery in the early 1930s. American Duncan Thomas bought the distillery and apparently tried to produce light bodied Lowland whisky by two distillations with the reflux column and water jacketed cooler on the spirit still, instead of the traditional triple distillation previously used at the distillery. The double distillation with reflux column pot still was used at Littlemill until its closure in 1994. A similar experimentation was conducted in the 1950s by the Canadian company Hiram Walker & Sons. Their agenda was to produce a variety of different malt whiskies for blending purposes. To increase the control of the distillation reflux they used rotating rectifier plates, which could be turned to vertical or horizontal position for less or more reflux. The first such still was installed at Inverleven malt distillery situated inside the grain distillery Dumbarton in 1956. The resulting spirit was called Lomond whisky, hence the name Lomond still used later to describe all the Scottish reflux still whiskies. The experiment was successful, and the Canadians went on to install Lomond stills at Glenburgie (to produce Glencraig), Miltonduff (to produce Mosstowie) and Scapa. Scapa was different from the others, as it used a Lomond still in the wash distillation to render the spirit "sweeter and cleaner".

Lomond wash still at Scapa

Littlemill distillery owner Duncan Thomas founded the Loch Lomond distillery in 1966 with the American company Barton distillers to produce a yet wider variety of spirits (7) by altering the settings of the rectifier plates, but also the length and angle of the lyne arm by a peculiar turning telescope lyne arm. These adjustable lyne arms were also installed in Mosstowie and Glencraig later on.

The Scapa reflux wash still experiment was discontinued in 1971. The official reason for removing the rectifier plates was that the tube and shell condensers made the wash still plates futile. That sounds odd since the tube and shell condensers had been used for a century by then. The Lomond stills in Miltonduff and Glenburgie were mothballed in 1981, as the surplus of whisky resulted in rationalisation of the business and eventually forced Hiram Walker to sell out all their Scottish distilleries in the mid 1980s. Littlemill was mothballed in 1994 and destroyed in a fire in 2004. Duncan Thomas and Bartons sold Loch Lomond in 1971 to a private company, which keeps the reflux still distilling alive in Scotland.

A hybrid Holstein still from Germany
Copper pot still with a rectification column and a dephlegmator (cooling head) and a steel condenser

REFERENCES AND FURTHER READING:
Barnard A. The whisky distilleries of the United Kingdom. Birlin ltd 1887
Forbes, RJ. Short history of the art of distillation. Brill 1948

Hume JR, Moss MS. The Making of Scotch Whisky

Morewood S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. Longman 1838.
Nettleton, W. The manufacture of spirits. London 1893
Reaich, D. Influence of copper on malt whisky character. In Proceedings of 5th Aviemore Conference on malting, brewing & distilling. 1998
Ronde I. Malt whisky yearbook 2015. MagDig 2014.
Russell I. Whisky. Elsevier 2003.

Townsend B. Scotch missed. Angel's share 2000.
Townsend B. The lost distilleries of Ireland, Neil Wilson 1997

Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.

Weir, RB. The history of the Distillers Company 1877-1939, Oxford Univ Press 1995

Scottish whisky mash bill

noreply@blogger.com (Teemu Strengell) — Fri, 06 Mar 2015 15:02:00 +0000

Malted barley is the main ingredient in Scotch malt whisky. Barley (Hordeum) is a member of grass family, just like most cereals in the world. There are two main types of barley: two-row and six-row. Both have six rows of seeds, but in the two-row varieties only two are fertile. The two-row varieties have usually plumper grains, less protein and husks and more fermentable sugars than the six-row varieties. The British malting barley varieties are and were almost exclusively of the two-rowed type, and the protein-rich six-row barley is mostly used for cattle feed. Barley can be sowed during the winter or in the spring, depending on the variety and the climate. Most distilling malts are made of spring barley, because they malt better with less dormancy issues. European brewers mostly use two-rowed barley, while Americans utilize mostly 6-rowed. Some varieties are naked, ie they do not have so much husks.

During the 17th and 18th century the main cereals grown in Scotland were barley, oats and rye. It is likely that all of them were used to produce distilled spirits (and whisky), although barley was probably favoured for its better enzyme activity. Additionally oats had too much husk for efficient mashing and rye tended to produce excess yeast growth. Mixed fermentations were probably often used, after all distilling was merely a way to preserve excess crop. Martin Martin in 1702 describes the practice on the Isle of Lewis: "The corn grown here is barley, oats and rye... Natives brew several sorts of liquors; as common Uisquebaugh, another called Trestarig, id est Aqua Vitae, three times distilled, which is strong and hot; a third sort is four times distilled Uisquebaugh-baul; id est Uisquebaugh...The Trestarig and Uisquebaugh-baul are made of oats". The oats were likely to produce a wash lower in alcohol and higher in congeners, so the process of three or four distillations makes sense. Multiple distillations and narrower cuts were most likely used to produce a palatable spirit, not so much to reach high alcohol strengths.

Chevallier barley was recently revived in Norwich by Dr Chris Ridout

During the 18th and 19th century the barley varieties used were local landraces, which were selected by the local farmers. In Scotland local landraces, probably most of the variations of Scotch Common, a two-row, narrow-eared, small-grained, early ripening variety, dominated until the 19th century. In colder climates, especially in the Northern Highlands some bere barley, a six-rowed landrace, was cultivated, but it was mostly used as cattle-feed. Most early 19th century English landrace varieties were probably close to Czech Hanna variety, a two-row, early ripening barley with a quite brittle straw. First generally successful variety in Britain was Cheval(l)ier, discovered in Suffolk, 1819. It spread across the country quite rapidly and most of the barley sown in the 1840's Britain was Chevalier, especially in the South. The other widely spread variety in England was Annat (1830) and in Scotland some of the Hanna varieties were still used in the late 19th century.

The price of maize and grain whisky (Weir 1995)

Malted barley was the main ingredient in both pot-still and column still whiskies in the 1830-40s, although column distillers began adding unmalted barley into the mash. In 1848 adjuncts, such as molasses, treacle and sugar were permitted in whisky production (1847 for beer) and further tax cuts made it possible for especially column distillers to produce whisky from a variety of raw materials, mainly from cheap American maize. Maize was about 30% cheaper than barley at the time and as the production in the USA increased during late 19th century, it quickly became the major ingredient of column still whisky. By 1877 the average grain whisky mash-bill was: maize 77%, barley 20%,oats 2,5%, wheat 0,4%, rye 0,02%, malted barley 0,14%. The grain for column distillers was bought predominantly from abroad, less than 1% of the total grains and 2-6% of the barley were sourced from UK at the time. Oats, rich in fibers, were in mainly to improve the draining. The role of rye was to propagate yeast, while barley provided the enzymes. The cheap maize, efficient continuous Coffey still and the crisis in wine/cognac industry helped the boom of grain whisky in late 19th century. Brewers turned to foreign barley in the late 19th century mainly because of better quality of the Danish malt, not so much for the price. The Irish distillers used a mixed grain bill from the late 19th century, usually consisting of barley malt (30-50%), unmalted barley (30-40%), oats (20-30%), rye (3-6%) and wheat (5-10%).

The pot-still malt whisky distillers were more traditional, even superstitious in their grain purchases compared to brewers and grain distillers. They used mostly local barley throughout the 19th century, although during the periods of bad harvests and/or higher whisky demands, as during the 1890's whisky boom, they were forced to use some foreign barley, mostly from Denmark, the Baltic and Morocco. There were other significant reasons for pot distillers to use local barley: They were trying to ban the grain distillers from marketing grain spirits as whisky or Scotch and proposed that only whisky made from Scottish grain could be called Scotch. The local farmers also bought much of the draff (waste product of the first distillation, great cattle feed) from the distilleries, so both benefited from direct sales to each other without any mediators. One likely explanation for the local sourcing of barley is the traditional and frankly sometimes superstitious approach on any improvement or change of the process or the product.

Beaven 1947

In the beginning of 20th century the predominant varieties were Annat, Goldthorpe, Archer, Spratt and Chevallier. After the World War I hybrid selections began to be made. Spratt-Archer and Plumage-Archer were popular and together comprised of 80% of malting barley until the World War II. The selections were made mostly based on the yield per acreage and the carbohydrate yield of the malt, flavour was rarely discussed. The foreign barley entered the distilling malt markets in 1920s, sourced mainly from Denmark and Chile (probably 6-rowed), and to some extent from Romania, Tunisia, Canada and Australia. Danish and Australian were preferred of for their quality, but for trade protectionist reasons the distillers (lead by DCL) agreed to by preferentially Scottish and English barley.

In the 1920s the prices of cereals varied widely and grain whisky was made from various ingredients based on the world market. Barley from California and Canada (small 6-row), maize from US and Argentina, oats from Scotland and Canada, even Brazilian manioc were used. The column grain distillers used the cheapest available raw materials, for example the maize bought from USA was usually grade 3, while the US domestic distillers used grade 1-2 maize.

During the WW II, Danish Kenia was grown widely for its better yields, however it was not good for malting and after WW II Pioneer (Kenia x Austrian Tshermarks) and Proctor (Plumage-Archer x Kenia) dominated until 1960 with a acreage up to 70%, although DCL seems to have preferred Zephyr. Due to rapid growth in whisky production in the 1950s, more English and foreign barley was used. If six-row barley was used, the smaller grains were sold to the distillers (more enzymes) and the plumper grain (more yield) to the brewers. Golden Promise and Maris Otter were introduced in 1965. Golden Promise became the barley of choice for distillers for its yield and enzyme activity until 1980s and Maris Otter was the brewers' malt, allegedly for its flavour. In the 1980s German Triumph and its many hybrids (Corgi, Natasha, Optic, Prisma, Camarge) surpassed the Golden Promise for their better yield and some winter varieties were introduced in Southern Scotland (Melanie, Halcyon, Regina). After that many different varieties have been developed and the suitable varieties for distilling and brewing are declared annually by Institute of Brewing and Distilling.

Improvement of spirit yield (Russell, 2003)

Brookes 2005

During the 20th century the acreage yield of barley has increased rapidly. Archer gave less than 3 tonnes per hectare as modern barleys for distilling malt give up to over 8 tonnes per hectare. Also the alcohol yield has improved drastically, from 300 litres of pure alcohol per tonne of dry malt to about 460 lpa/t.

Recently old varieties have been revived, mostly due to growing craft beer movement, but also by some malt distilleries. Bere barley was used in whisky production in Highland Park until 1926 and has since been used mainly for bere bannocks, but also for malt whisky. Bere was 6-row barley variety originating probably from northern Scandinavia with long stem and rapid growth (therefore also called 90-day-barley). Michel Couvreur revived the bere whisky in 1985 when he used bere from Orkney to distill whisky at Edradour. Since then at least Arran, Springbank and Bruichladdich have released bere whisky.

Sadly, there are no scientific comparisons between the flavour of different barley varieties. The early malting varieties were proportionally higher in protein and fat but lower in carbohydrates. Steeping times were much longer, probably because lack of knowledge and to some extent because of dormancy-prone barley varieties. The germination times were longer and the temperatures in floor maltings were more uneven than in modern maltings. These differences most likely made the wort more prone to infections of wild yeast and lactobacilli, along with mostly longer fermentations and lower starting gravity. The consistency was probably more viscous due to greater proportion of betaglucans to alpha-amylases. So the wort was likely to have more husks, dead yeast, autolysis products, lactobacilli, oils, diacetyl, esters (from acids and alcohols) and thicker in consistency causing easier burning in the wash still. The result was likely to be oilier, more sulphury and fruity spirit with more higher alcohols (fusels) and more furfural (from the husks, providing nutty aroma), assuming that the other factors were kept constant. It is unlikely that there are considerable differences within the modern barley varieties in terms of distilling, since the specifications for malting barley are quite strict. However, there is proof that the change of barley variety also changes the lactobacilli flora in the distillery, which might have at least some effect to the spirit if long fermentation times are used. The practice of malting (floor malting/industrial malting) has probably greater effect on flavour than the barley variety.

Maize mill at Dumbarton (I.Hume)

Because the use of enzyme additions is prohibited in Scottish whisky, the grain distilleries continue to use about 10% of malted barley in their mashes to guarantee sufficient enzyme content for starch degradation. Maize from the USA dominated the Scotch grain whisky mash bill from 1860s until early 1980s, excluding the war years. Since then, wheat has surpassed it, mainly because the trade regulations and taxes, not so much because of the actual cost of raw materials. Actually the price of unmalted barley has been quite competitive against maize and wheat in recent decades, but the processing problems have steered most grain distillers to wheat, mainly from France in the 1980s, but lately predominantly from the UK, with a fraction imported from Germany and France. North British is the last Scottish distillery to use predominantly maize, as the other "maize distillery" Dumbarton was closed in 2002. Some maize is still used at least occasionally in most grain distilleries, most likely to minimize viscosity problems. Maize has lower viscosity of mash compared to wheat and malted barley, because of lower amounts of betaglucan and pentoses. Since 1990s the Scottish distillers' maize has been bought exclusively from southern France due to trade barriers of EU. Bakers and farmers prefer high nitrogen wheat, so there is not a serious competition over low-nitrogen grains and distillers' wheat does not carry a price premium.

Biernacka&Wardencki 2013

The differences between wheat and maize spirits are surprisingly clear, there are less differences between wheat, triticale and rye spirits. Maize spirits contain about ten times less higher alcohols than the other grain whiskies, but have proportionally higher levels of esters (fruity). The higher amount of pentoses in maize also contribute to the higher furfural (nutty) content. The greater variety and amount of higher alcohols in wheat spirit account to more harsh, spirity and solventy notes in young spirit, but a likely to develop to a variety of acetals and esters, with more fruity aromas. The popcorn aroma sometimes present in blended whisky is likely to come from too much feints from the malt whisky involved, not from the grain component. The mouthfeel of wheat whisky can be oilier or waxier due to more arabinoxylans, while corn whisky is usually described cleaner and shorter.

Biernacka&Wardencki 2013

REFERENCES
Agu RC et al. Production of grain whisky and ethanol from wheat, maize and other cereals. J Inst Brew 2006;112;4;314-323
Beal, AD & Mottram DS. Compounds contributing to the characteristic aroma of malted barley. J Agric Food Chem 1994;42;2880-4
Biernacka P & Wardencki W. Volatiole composition of raw spirits of different botanical origin. J Inst Brew 2012;118;393-400
Beaven, ES. Barley. Duckworth 1947
Briggs, D. Malts and Malting, Blackie 1998
Bringhurst TA. Barley research in realtion to Scotch whisky production. J Inst Brew 2015;1;1-18
Brookes, P. Barley Breeding and development in the UK, an historical perspective. Brew Hist 2005;121;25-39
Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Campbell I (ed). Proceedings of the Third Aviemore Conference on Malting, Brewing and Distilling. Intitute of brewing, 1990.
Collins TS et al. Profiling of nonvolatiles in whiskeys. Food Chem 2014;163;186-196
Cramer ACJ et al. Analysis of volatile compounds from various types of barley cultivars. J Agric Food Chem 2005;53;7526-31
Dong L et al. Characterization of volatile aroma compounds in different brewing barley cultivars. Sci Food Agr 2014
Hoff S et al. Influence of barley varieties on wort quality and performance. J Agric Food Chem 2013;61;1968-76
Hornsey, IS. A History of Beer and Brewing. Royal Society of Chemistry 2003
Lloyd, WJW. Adjuncts. Centenary review. J Inst Brew 1986;92;336-345
Mallett, J. Malt. Brewer's Publications 2014.
Martin, M. A description of the Western Isles. 1702
Martin, P & Chang, X. Bere whisky- rediscovering the spirit of an old barley. Brew Dist Int 2008/4;6;41-43
Mather, RT & Willkie, RT. Distillers' grain manual. Seagram, 1942
Piggott JR et al (ed). The science and technology of whiskies. Longman 1989
Priest, FG & Campbell I (ed). Current developments in brewing and distilling. Aviemore conference 1982.
Robson, F. Cameronbridge, a distilling giant. Brewer Int 2001;1;4;16-19
Russell I (ed). Whisky, technology, production and marketing. Academic Press 2003
Weir, RB. History of the Distillers Company 1877-1939. Oxford 1995.

Chill filtration

noreply@blogger.com (Teemu Strengell) — Tue, 18 Nov 2014 12:43:00 +0000

Same whisky, chilled with a drop of water on the left

Most of the Scotch whisky in the market is filtered in some way before bottling. The methods vary from crude physical filtering (ie spirit is run through a cloth or a cellulose sheet) to temperature and pressure controlled nanofiltering systems.

The main reasons for filtering the spirits are removing any solid components, improving the flavour and avoiding the haze formation later in the bottle or glass.

Spirits have been chill filtered at least from the late 14th century. Russian vodka was traditionally rapidly cooled after distillation with ice. The excess water transformed into ice and most of the oils hardened on top of that. Filtering became common before the 17th century. The early filters were usually made of cloth (felt, cotton), but also of paper, sand and charcoal. Chemical purification was also used quite early on, just as with wine, mead or beer. Spirit cleansing additives of the 17th and 18th century included ash, potash, burnt wormwood, and the gentry also used milk, eggs, fresh black bread, soda and isinglass to produce top quality vodka.

Charcoal in Jack Daniel's distillery (alcademics.com)

Coal filtering was also widely used in USA and Canada in the early 19th century. In 1810's Kentucky "layers of white flannel, clean white sand and pulverised charcoal (about 20 inches thick layer) from good green wood such as sugar tree hickory" were used as a filter. The now famous Lincoln county process consisting of maple wood coal filtration at a thickness of 10 feet was invented in 1825 by Alfred Eaton and is still used by Jack Daniel's and George Dickel. Active charcoal was widely used from the start of the 20th century. The first written evidences of active charcoal filters are from 1785 from St Petersburg, Russia. Farmacist T.Y. Lowitz found that raw distillates became clearer and less harsh tasting after treatment with "raw coal". The activated coal filtering was patented in 1901 in Austria and in 1907 in Russia and used widely ever since, especially in vodka production.

Sand and coal filter tanks in Zhitomir vodka distillery

The distillers filter their spirits for various reasons, most of which are based on traditional practices and empirical evidence, not much has been released as scientific papers. In Tennesee, the Lincoln County process is believed to reduce fusel oils and harsh flavours, resulting in a "less grainy" spirit, according to John Lunn, the master distiller of George Dickel. Most bourbons are filtered before and after aging with active charcoal, usually said to "mellow" the taste. In China, Japan and Taiwan the rice spirits are filtered to remove higher alcohols (fusels) to enhance the flavour. The vodka producers usually just try to remove any colour or taste to render the spirit "clean". Scotch whisky producers claim that their filtering does not affect the flavour and only prevents the haze formation in the bottle or glass. Actually, charcoal is not very efficient in removing oils from the spirit, at least at higher alcoholic strengths and the normal filtration of rice spirits removes only a small fraction of higher alcohols, although an extremely efficient nanofiltration can reduce higher alcohols up to 44%. Interestingly, the amounts of higher alcohols has quite dramatically dropped during the 20th century, which probably diminishes the clouding, but also must affect the flavour, both directly and through lesser high chain ester formation.

	EU limit [g/l]	Modern spirit, est.	Analysis 1905	Analysis 1966
Scotch malt	10	~ 1	1,5-3,5	2,7-3,9
Scotch blend	10	<1	0,5-1,9	1,7-2,2
Scotch grain	10	<1	0,5-3,0	0,7-1,3
Bourbon	10	~ 1,5		5,9-6,8
Rice spirits	10	2-5
Rum	2,25
Fruit brandies	2
Marc	1,4			3,5-4,5
Brandy	1,25	<1		1,5-5,7
Canadian whisky	10			1,15
Irish whisky	10			6,95

Amount of higher alcohols in different spirits [g/l]

The haze formation occurs when the long chain fatty esters become insoluble in lower temperatures or at lower alcoholic strengths. The most crucial esters in haze formation in whiskies are ethyl laureate (ethyl-dodecanoate), ethyl-palmitate (ethyl-hexadecanoate) and ethyl-9-hexadeanoate (ethyl-palmitoleate). Alcocol content of 45% abv is believed to be a crucial limit for these long chain esters to percipitate in room temperature. Other compounds responsible for the cloudiness are high molecular weight lipids, especially sitosterol beta-D-glucoside (probably cask-derived) and slightly ethanol-soluble lignins from the cask.

The haze-forming long chain esters are not very aromatic, ethyl laureate gives some floral, fruity and waxy aromas, as ethyl palmitate and ethyl palmitoleate mostly contribute to the mouthfeel (waxy, oily), although they are reported to give some aromas of coconut and fruits. Probably the more important factor is their ability to act as a surfactant and to enhance/suppress other aromas.

(Coal) filtering increases the formation of short esters and the conversion of aldehydes and ketones to alcohols, probably because of the slight oxiditation caused by the process. On the other hand, some (7%) ethyl acetate (pear-drops) was removed in a typical Scotch filtration, so the net effect remains unclear. The highly efficient nanofiltration and active coal filtration techniques used by brandy and vodka industries remove great deal of long esters and some terpenes. Even a light filtration removed all of the nerol (rose,lemongrass) from apricot brandy and the same probably happens in Scotch whisky filtration. Studies on Glenlivet malt whisky indicate that significant amount of gallic acid was removed in filtering, but the same study found no difference on nosing aroma.

Plate and frame filter in a bottling plant

A typical filtering method used in Scotch whisky industry is a plate and frame filtration with cellulose sheets, medium pressure and cool temperature. Depending on the source the temperature of whisky is lowered usually to +5 - +10C, although some apparently use even colder temperatures (down to -10C?). According to Glenmorangie the cold stabilisation time is 3 hours and apparently up to 24h in some other bottling plants. In the 1990s all of the filters used in Scotch whisky industry were of the plate and frame type. Some distillers have at least experimented with easier and cheaper membrane filters, but there is little information about whether they are in use at a larger scale. The pressure use in the plate and frame filters is usually between 20-60 psi (138-414 KPa), a higher pressure means faster but less complete filtration. The particle retention size is 5-7µm, at least in one bottling plant. Compared to the modern nanofilters at 10nm (0,001µm), that is quite crude.

Plate and frame filter (whisky.com)

Because the filtration processes are not uniform in the Scotch industry, it is not clear how much the process affects the flavour. Certainly you can change the flavour profile and the mouthfeel of an estery and oaky whisky with slow cold filtration. A too strict filtration would likely dimish waxy/oily mouthfeel and floral, fruity and oaky aromas. Whether the current filtering practices do that, is uncertain.

References and further reading.
Braus H et al. Isolation and identification of a sterol glucoside from whiskey. Agr Food Chem 1957;5(6);458-9
Da Porto C. Effects of chill filtration on the composition of grape spirit. Wein-Wissenschaft 2000;55(1);7-12
Duarte FC et al. Physicochemical and sensory changes in aged sugarcane spirit submitted to filtering with activated carbon filter. Ciênc Tecnol Aliment.,2012;32(3);471-477
Glaub, R et al. Effects of various filter systems on sensory quality of fruit brandies. Kleinbrennerei 1998;50 (1);6–12
Himmelstein L. The king of vodka. Harper 2010
Hsieh CW et al. Develop a novel method for removing fusel alcohols from rice spirits using nanofiltration. Food Sci 2010;75(2); 25-29
Ko W et al. Removal of higher fatty acid esters from Taiwanese rice-spirits by nanofiltration. p353. In Distilled spirits, ed Walker GM et al NOttingham Univ Press 2012.
Lachenmeier D et al. Defining maximum levels of higher alcohols in alcoholic beverages and surrogate alcohol products. Reg Tox Pharm 2008;50;313-321
Miljic UD et al. The application of sheet filters in treatment of fruit brandy after cold stabilisation. Acta per tech 2002;44;87-93
Taylor AJ, Mottam DS. Flavour science: Recent developments, RCS 1996
Persson KM. Med kol och kolonn. Spiritus 2005;7
Piggott JR et ak. The science and technology of whiskies. Longman 1989
Pirie G et al. Membrane filtration of whisky. Food & Drink 2000; p9-13. IChemE 2000.
Pokhlebkin W. A history of vodka. Verso, 1992
Puskas V et al. Influence of cold stabilisation and chill membrane filtration on volatile compounds of apricot brandy. Food Bioprod Proc 2013;91;348-351
Schidrowitz P, Kaye F. The determination of higher alcohols in spirits. Analyst 1906;31;181-194
Singer DD. The analysis and composition of potable spirits. Analyst 1966;91;127-134
Wisniewski I. Filtering out. Whisky Magazine 2011;97;27
Malt Maniacs E-pistle: http://www.maltmaniacs.net/E-pistles/Malt-Maniacs-2011-06-Chill-filtration-and-cloud-formation-in-whisky.pdf
Whisky.com study: http://www.whisky.com/information/knowledge/science/study-on-the-chill-filtration-of-scotch-single-malt-whiskies.html

Copper

noreply@blogger.com (Teemu Strengell) — Sat, 18 Oct 2014 05:49:00 +0000

Glenfiddich still room

Scotch malt whisky is distilled in copper pot stills. Copper is used for its malleability and heat conductivity, but mainly because it is believed to render the spirit less sulphury and more refined. Surprisingly little is known about the mechanisms and chemistry behind the positive effects of copper to the spirit.

Copper is the traditional material for Scottish stills, but the first distillers of aqua vitae were most likely using pots of clay or glass. In Asia, clay and porcelain pots with bamboo condensers were used. Quite minute quantities of spirits were prepared before the 14th century. As metallurgy improved and distilling became a larger scale operation, the stills were forged from tin, iron, brass and copper. Copper was easiest to keep clean, not too heavy and relatively easy to forge, so it became the common still material, at least in Britain and France quite early on, probably in the 15th century.

Indian still from 18th century

According to Samuel Morewood in 1838, most European distillers were using copper stills, although poorer distillers still used some tin, pewter and even wooden stills. Copper was preferred and Scottish illicit distillers considered that at least the bottom and the worm of the still should be copper, but tin was often used in the body of stills. At the time Indian distillers preferred clay pots with copper head, which was cooled by cowdung which was kept moist by cool water. In Java copper stills and Banca tin worms were used. In the British Caribbean (Jamaica, Trinidad, Barbados) mostly copper stills were used, but in the French and Dutch Caribbean (Guadaloupe, Marie Galante, Martinique, Guyana, St Martin) there were many different still types, probably of French inspiration, constructed of copper, iron and wood.

Copper is often claimed to suppress the amount of sulphury compounds in the spirit, but there is really quite a little research or even theoretical understanding about the phenomenon. The most predominant effect promoting the sulphury aroma in spirits is dimethyl trisuphide (DMTS). Its perception treshold is about 0,1µg/litre and the typical concentrations in spirits vary between 1-6µg/litre. The amount of DMTS has been shown to diminish in the spirit by the copper influence. However, not just any copper influence has that effect. For example, by using copper salts in a glass still increases DMTS, but copper wool in a glass still decreases DMTS, just not as much as a copper still. In addition, an used and patinated copper still seems to be more effective in DMTS-reduction compared to clean copper. To make things even more complex, the other metal ions and the antioxidant potential of the wash change the settings of the system once more. For example, iron decreases the copper effect, but ascorbate (by acid or antioxidant effect?) increases the DMTS formation. Most common aromatic sulphury compounds present in the wash are (pot) distilled just about in the same quantities over to the spirit, whether a copper or steel still is used, including DMS, DMDS, MMFDS, thiophene, thianaphthene and S-methyl thioacetate.

Levels of sulphur compounds in new make from copper and stainless steel stills (Harrison 2011)

Another important effect of copper is its catalyst role in converting thiols and mercaptans to usually less pungent compounds in presence of carbonyls. Methanethiol (CH3SH) is abundant in nature and in small quantities it contributes to the aromas of nuts and cheeses, but in higher concentrations it smells like rotten vegetables. Mercaptans and thiols are formed in some extent by the yeasts as byproducts, but especially in the event of anaerobic (non-lactic) bacteria infection of the wort.

There is some evidence of increased ester formation from acids and alcohols during the distillation, but that may happen in higher temperatures anyway and have nothing to do with the copper. Copper seems to have some effect on phenols, decreasing slightly the amount in the distilled spirit.

Copper plates in a column still

Ethyl carbamate (EC, urethane) was a hot topic in the 1980s, as it was found to be carcinogenic and to increase during maturation phase of spirits. At the time various whiskies, especially grain or bourbon whiskies from stainless steel column stills were producing spirits with way too much EC and the concentrations seemed only to increase during maturation. It was found that copper in the ascending phase on still decreased EC dramatically and copper was (re)introduced into column stills. Adversely copper salts in the new make does catalyse the EC formation during the maturation, so most grain distillers use only stainless steel in the condensers to dimish the amount of copper residues in the new make.

The most influential part of distillation in terms of sulphur (DMTS) removal is in the spirit still body and interestingly in the vapour phase of the wash still, but not as much in the wash still body or the spirit still vapour phase. Alcohol concentration might play a role in the catalyst properties of copper. The spirit still condensers at the end of the second distillation have the least effect to the DMTS removal, on the other hand (at least in the column stills) the late phase condensers are shown to be important in conversion of dimethyl sulphide (DMS) to less aromatic sulphide.

DMTS in the new make.(C=copper still, S=stainless steel still, S1=copper in wash still body, S2=copper in wash still lyne arm, S3=copper in wash condenser, S4=copper in spirit still body, S5=copper in spirit still lyne arm, S6=copper in spirit condenser) (Harrison 2011)

Reflux is important factor in copper influence. It means the amount of vapour condensed and trickled back down to the still from the head and lyne arm instead over to the condenser. Reflux depends on the charge (fill level) of the still, whether the wash is cooled or preheated, the shape of the still, the speed of distillation and the cooling of the still and the condensers. High reflux is achieved by low preheated charge, big tall narrow stills with boiling ball and steam coils, ascending lyne arm and efficiently cooled tube condensers. High reflux means lower DMTS and phenols, but higher esters and high alcohols, producing fruity clean spirit. Low reflux gives full, meaty, phenolic, robust new make. Esters apparently follow an U-curve, so that very low or high reflux produces more esters than an average one.

Lomond wash still in Scapa

In the 1950s a Canadian company Hiram Walker tried to gain access to Scottish malt whisky markets. They owned six malt distilleries and the Ballantines brand. Only six different malts were considered inadequate for blend production and at the time competition was harsh, so they decided to experiment with pot stills installed with rectifier plates inside the head of the still. By turning and adjusting the number of the plates they were able to adjust the reflux and copper contact. First such still was installed at Inverleven (inside the grain distillery Dumbarton) in 1956 and the resulting spirit was called Lomond whisky, hence the name Lomond still. The experiment was successful, and Hiram Walker went on to install Lomond stills at Glenburgie (to produce Glencraig), Miltonduff (Mosstowie) and Scapa. Scapa was different from the other, as it used Lomond still in the wash distillation to render the spirit "sweeter and cleaner". Loch Lomond distillery was founded in 1966 and it produced a variety of spirits (7) by altering the settings of the rectifier plates, but also the length and angle of the lyne arm by a peculiar turning telescope lyne arm, which was also installed in Mosstowie and Glencraig later on. Scapa experiment was discontinued in 1971, as better condensers made the wash still plates futile. The Lomond stills in Mosstowie and Glencraig were mothballed in 1983, as the surplus of whisky resulted in rationalisation of the business. The rectifier plates did change the spirit qualities, bu according to still men, they were very hard to keep clean and they accumulated lots of residue when turned fully horizontally. The cleaning problem became even worse by the introduction of solid yeast in the 1970s. Probably tube condensers were easier and even more effective in sulphur removal, although maybe ester formation was theoretically better in the rectifier plates. Loch Lomond distillery still produces Lomond-style whisky.

Just to put the theory to the test, below are the lyne arm angles and spirit still sizes of 24 Scottish malt distilleries compared against lightness-richness value given for the basic ~12yo malt of the distillery by Dave Broom in The World Atlas of Whisky. There is some, but not significant correlation between the lyne arm angle and the richness of whisky, but no correlation between the spirit still size and the perceived richness. Of course there are many other aspects affecting the products of the distilleries. Would have been too simple, if there was a clear correlation between either one...

Some correlation between lyne arm angle and richness of the basic OB

No correlation between spirit still size and richness of the basic OB

References and further reading:
Alcarde A et al. Ethyl carbamate kinetics in double distillation of sugar cane spirit. J Inst Brew 2012;118;352-5
Broom D. World atlas of whisky. MItchell Beazley 2010
Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Forbes, RJ. Short history of the art of distillation. Brill 1948
Harrison, B et al. The Impact of Copper in Different Parts of Malt Whisky Pot Stills on New Make Spirit Composition and Aroma. J Inst Brew 2011;117(1);106-112
Hernández-Gómez L et al. Melon fruit distillates. Food Chem 2003;82;539-543
Jack, FR et al. Sensory implications of modifying distillation practice in Scotch malt whisky production. In Distilled Spirits, ed Bryce JH, Piggott JR, Stewart GG. Nottingham Univ Press 2008.
Lima U et al. Influence of fast and slow distillation on ethyl carbamate content and on coefficient of non-alcohol components in Brazilian sugarcane spirits. J Inst Brew 2012;118;305-8
Masuda, M and Nishimura, K. Changes in volatile sulfur compounds of whisky during aging. J Food Sci 1982; 47(1); 101-5
Monica Lee KY et al. Origins of flavour in whiskies and a revised flavour wheel. J Inst Brew 2001;107(5);287-313
Morewood S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. Longman 1838.
Nedjma M, Hoffmann N. Hydrogen sulfide reactivity with thiols in the presence of copper in hydroalcoholic solutions or cognac brandies. J Agric Food Chem 1996;44;3935-38
Nóbrega I et al. Ethyl carbamate in cachaça. Food Chem 2011;127;1243-7
Prado-Ramírez R et al. The role of distillation on the quality of tequila. Int J Food Sci Tech 2005;40;701-8
Reaich, D. Influence of copper on malt whisky character. In Proceedings of 5th Aviemore Conference on malting, brewing & distilling. 1998
Riachi L et al. Review of ethyl carbamate and polycyclic aromatic hydrocarbon contamination risk in cachaça and other Brazilian sugarcane spirits. Food Chem 2014;149;159-169
Russell I. Whisky. Elsevier 2003.
Walker GM, Hughes PS (ed). Distilled spirits, new horizons: energy, environment and enlightenment. Nottingham Univ Press, 2010

Fermentation waters

noreply@blogger.com (Teemu Strengell) — Wed, 16 Apr 2014 16:42:00 +0000

Glenlivet is one of the few Scottish distilleries using hard water,
but nobody told the AD.

Water is used in several phases of whisky production: steeping, mashing, cooling and dilution. Formerly water mills provided much of the energy needed in many distilleries as well. Distilleries have often been founded into places where water is easily available and it is believed at least in the marketing departments that fresh spring water or picturesque peaty burns play a significant role in the manufacturing process.

The most important attributes of steeping and mashing water are its hardness, pH, overall mineral content and microbiological purity.

Water hardness means the concentration of multivalent cations in the water, ie the amount of ions with a charge of +2 or more (mainly calcium and magnesium) and it is usually expressed as concentration of calcium carbonate (CaCO3) in the water. Soft water is defined as containing under 40-100 mg/l and hard water over 80-200 mg/l of CaCO3, depending on the source.

The pH (pondus hydrogenii) of water means the activity of hydrogen atoms in the water. The pH value describes the acidity of the water in logarithmic scale, ie pH 4 is ten times more acidic than pH 5 and hundred times more acidic than pH 6.

The malt or grain is another source of acidity in the mash. The darker the roast of the malt, the more acidic it gets. Therefore soft alkaline water is often preferred for brewing pale malts and hard water for darker acidic malts. The malts used in whisky production are as pale as possible to ensure the best alcohol yield. The commonly desired pH for mash is about 5-5,5, a lower pH might cause excessive lactic acid bacteria production and a higher pH a slower or incomplete fermentation. Calcium is the most important mineral affecting both the pH and water hardness. Calcium itself does not taste of anything at usual concentrations, but it lowers the pH, increases water hardness and yeast flocculation and might reduce magnesium making the flavour less sour.

Other important ions in the brewing waters are sodium (Na+) and the common anions; sulphate (SO4^-²), chloride (Cl-) and carbonate (CO3^-²). Sodium softens the water by decreasing the effect of CaCO3 and at higher concentrations (over 50 ppm) makes the water sweet, or even salty (>150 ppm) and sour (>250 ppm). Sulphate enhances bitter, dry and sulphury flavours, complimenting the hoppy aromas of beers and providing antibacterial influence in both fermentation and bottle-aging, reducing the lactic acid bacteria growth. Chloride enhances malty flavour, but at high concentrations it might give pasty, salty or chlorine aromas. None of Scottish distilleries use chlorinated water for their fermentations.

The local water quality was probably one of the reasons why brewers in Burton-on-Trent and Edinburgh went for bitter highly hopped IPAs (high CaSO4), in Pilzen for light crisp lagers (extremely soft water), in Münich for darker lagers (higher CaCO3), in Dublin for dark stout (high CO3^-², low Na+ and relatively low Ca+2) and in London for dark sweet porter (high CaCO3 and NaCO3).

Ion concentrations in typical brewing waters (Maltman 2003)

All rainwater is soft, it is in the water reservoirs it acquires its hardness. The longer the water spends in rivers, lochs or underground aquifers, the more time it has to gain solubles from the ground. The geology also plays a significant part, as hard granite or quartz is less soluble than limestone or chalk and very different from young basalt.

Spring	Burn/River	Loch	Well	Mains
Ardmore	Aberfeldy	Ardbeg	Auchroisk	Devanha
Balvenie	Aberlour	Auchentoshan	Glenlivet	Dundashill
Benriach	Allt-a-bhainne	Bruichladdich	Macallan	Oban
Benromach	Aultmore	Cambus	St Magdalene	Strathdee
Cardhu	Balblair	Cameronbridge	Saucel
Convalmore	Balmenach	Caol Ila	Strathisla
Craigellachie	Benrinnes	Port Dundas
Edradour	Bladnoch	Millburn
Fettercairn	Blair Athol	Garnheath
Glenallachie	Bowmore	Glen Flagler
Glenburngie	Braes	Islabrae
Glencadam	Brora	Killyloch
Glendullan	Bunnahabhain	Kinclaith
Glen Elgin	Caledonian	Nort Port
Glenfarclas	Caperdonich	Port Ellen
Glenfiddich	Clynelish	Provanmill
Glen Garioch	Cragganmore	Pulteney
Glenglassaugh	Daftmill	Riechlachan
Glen Grant	Dailuaine	Rosebank
Glenkinchie	Dallas Dhu	Springbank
Glenmorangie	Dalmore	Longrow
Highland Park	Dalwhinnie	Springside
Longmorn	Deanston	Strathclyde
Mortlach	Glen Albyn	Tobermory
Pittyvaich	Glendronach
Royal Lochnagar	Glen Esk
Strathmill	Glengoyne
Tamdhu	Glenlochy
Tamnavulin	Glenlossie
Teaninich	Glen Mhor
Tomintoul	Glen Moray
	Lochside
	Macduff
	Mannochmore
	Man O'Hoy
	Miltonduff
	Royal Brackla
	Scapa
	Speyburn
	Talisker
	Tomatin
	Tormore
	Tullibardine

Water sources for mashing, hard waters in bold (Modified from Udo, 2006)

Scotland is divided into various different geological areas basically by several southwest-northeast-lines as illustrated below.

Geological map of Scotland (www.scottishgeology.com)

Speyside and the eastern part of Islay lie on the Dalradian rocks, formed about 570 million years ago and consisting mainly of metamorphosed sedimentary mudstone (schist and quartzite) with some granite hills. The rocks are old and resistant, therefore contributing little to the water, rendering it usually very soft, slightly alkaline and low sulphur. Notable exceptions are Glenlivet and Aberlour, which lie on top of granite-rich soil containing some limestone, rendering the water somewhat harder, especially from wells.

Geology of River Spey (www.snh.org.uk)

The Moray Firth at the Great Glen Fault there is essentially a river delta with mud and sand carried by the rivers, consisting of especially old red sandstone. The red colour comes mainly from iron, but the porous sandstone is also rich in calcium and magnesium, rendering the water in the Northern Highlands and Orkney significantly harder than in the Speyside. The water of Islay lies somewhere in between.

Typical waters from Scotland (UisgeSource)

Several American distillers believe in hard, low-iron water

However, many distilleries do process the waters they use. Apparently all the distilleries use at least ion-exchange methods for their bottling (dilution) water, but not necessarily for the reduction right after distilling (to bring the new make spirit down to 63.4% abv). None use chlorinated water for mashing or dilution nowadays. In the earlier part of the 20th century local bottling water was used and there were complaints that London water turned the whisky blue and cloudy whereas Speyside water did not, probably due to harder water of London. Although there are several breweries applying reverse osmosis (demineralization) and specifically mineralized (Burtonized) waters, these methods are not used in the distilling industry, or at least they are not made public. Water softening with resins is not used, and it could be detrimental because it tends to increase the sodium levels. Grain distilleries might benefit from hard water, as the calcium induces enzyme activity and lower malt contents and faster fermentations could be possible, although it is not entirely clear whether the mineralization of mashing waters is allowed by the law and the Scotch Whisky Association.

So, fermentation waters affect the quality of mash. The minerals themselves do not significantly distill into the spirit, but they affect the fermentation process before it. Soft water probably produces more faster fermentations and lactic acid bacteria growth generally resulting in heavier spirits, as the harder Highland waters produce cleaner and sweeter spirits. Iron is considered as a fault in brewing water and it is likely to produce less estery, fruity spirits. Zinc might do the same at higher concentrations, but is vital for yeast cells in lower concentrations. Peaty water does not provide enough phenols to render the spirit peaty, but higher amount of organics in the fermentation water does produce more esters and less higher alcohols, probably due to greater bacterial growth and yeast autolysis. Fermentation water quality is important to the quality of whisky, but in a different way it has been marketed.

Effect of brewing water to the spirit sensory quality (Wilson, 2010)

REFERENCES AND FURTHER READING
Cribb, S&J. Whisky on the rocks. Earthwise, 1998
Geikie, A. The Scenery of Scotland viewed in connection with its Physical Geology. Macmillan 1887.
Goldamer, T. Brewer's handbook. Apex, 2008
Maltman, A. Wine, beer and whisky: The role of geology. GeologyToday 2003;19;1;22-29
Palmer, J & Kaminski, C. Water, a comprehensive guide for brewers. Brewers Assoc., 2013
Scottish Natural Heritage. http://www.snh.org.uk/pdfs/consults/spey/speyreport.pdf

Wilson, CA et al. The role of water composition on malt spirit quality. Nottingham Univ Press, 2010

Bengt Thorbjörnson in Scotland, 1929

noreply@blogger.com (Teemu Strengell) — Sat, 01 Feb 2014 18:40:00 +0000

Bengt Thorbjörnson (1891-1975) was a Swedish chemical engineer. After graduating from Kungliga Tekniska Högskolan of Stockholm he worked in sulphite factory in Bergvik (1916-1917), which manufactured sulphite spirits as a side product from 1911 at least until 1917. In 1917 he moved to Kramfors to work in a cellulose factory (1917-24) also producing industrial spirits as a side product. After a short spell at a margarin factory in Kalmar (1924-26) and a visit to Nashwalk Pulp & Paper Co in USA (1924-1925) he was appointed as the chief chemical engineer for Vin & Sprit AB (Wine & Spirit). He continued to work for the biggest Swedish alcohol producer for 30 years until 1957.

Bengt Thorbjörnson on the left

Thorbjörnson toured Scottish whisky retailers and distillers in 1929-1930. The main object was to investigate whether it was profitable to start whisky production in Sweden. After the tour the Finnish alcohol monopoly consulted Thorbjörnson on the same subject and the record of the Scottish tour is still available in Swedish from the Kansallisarkisto (The National Archive) of Helsinki. Thorbjörnson visited the warehouses of W.H. Chaplin, John Walker & Son and The Distillers Company, as well as the distilleries in Caledonian, Mortlach, Cardow (Cardhu), Glen-Mhor, Glen Albyn and Adelphi.

He preferred the Highland malts and considered the Campbeltown malts were "lacking midtaste". The factors most affecting the flavour of whisky according to his studies were: 1) Water, which should be low in calcium. The water of River Spey was good as it ran through soil rich in granite and sand. 2) Climate, which should be quite cold but even to allow long stable distilling times. 3) Amount of peat used in drying the malt. 4) Bacteriae flora, as the local bacteriae influenced the quality of the brew. 5) Experience of staff.

The first place to visit was the wine and spirit retailer W.H.Chaplin & Co in London, who were at the time the sole representatives of the popular Long John brand. Their warehouse at Tower Hill consisted of 10 floors, of which 3 were underground. Huge glazed concrete cisterns (136 000 l) were used to vat and cold-chill-filter port wine. The whisky was vatted on demand in smaller concrete vats of size about 22 000 litres from different casks and different distilleries. According to other sources, Ben Nevis was the leading malt for Long John.

At John Walker & Son Thorbjörnson was hosted by the manager Sir Alexander Walker. At the time their Johnnie Walker blend was the most sold whisky brand in the world. Only sherry casks were used at the time. About 20% of them were new casks seasoned with sherry and the rest were refill casks rejuvenated with a small amount (about 35 litres) of sweet dark sherry for six weeks during which they were turned regularly. After the sherry-seasoning they are treated with pressure to impregnate more sherry into the wood. The sherry in the cask was then poured off and used several times for other casks. The pressure treatment had been developed by WP Lowrie in late 19th century and at the time of Thorbjörnson's visit it was used by many other blenders and distilleries as well. The Walkers had recently shifted to mainly hogshead size casks to ensure even quality. At the present time the Johnnie Walker recipe consisted of 10 parts Highland malt (Mortlach, Benrinnes, Ord, Cardow, Glenlossie, Dailuaine, Aultmore, Coleburn or Clynelish), 2 parts of Islay malt (Talisker (classified as Islay!), Caol Ila or Lagavulin) and 2 parts of Lowland malt (Rosebank or Glenkinchie). The blended malt was then again blended with grain whisky (mostly Caledonian) and the malt content varied between 40-60%. Long John blend consisted of 65% grain, 15% Lowland malt, 15% Highland malt and 5% Islay malts.

Caledonian distillery in 1966 (scotlandsplaces.gov.uk)

Caledonian grain distillery produced 40 000 gallons per week, which equalled 9 000 000 litres 50% abv- spirit per year. Maize was the most common cereal, but wheat and barley were sometimes used, too. About 30% of the mash came from barley malt dried over coal fire to gain diastase power. The maize flour was pressure cooked to prevent bacterial contamination. Brewers' yeast from Edinburgh was used to ferment in covered washbacks of 225 000 litres capacity (Cardow used pressed yeast). Carbon dioxide was collected and sold to mineral water producers. Column distillation with 20 plates in the analyser and 40 plates in the rectifier was used to produce new make spirit of 67 degrees over proof (95,3% ABV). The spirit was cut with water to 11 over proof (63,4% abv) for maturation. Draff was given for free to farmers. At the Adelphi grain distillery weekly production was 36 000 gallons/week and the only significant differences were the cooking of maize (not pressurised in Adelphi) and the fermentation time (72h in Adelphi, 96h in Caledonian). About 125 men were employed in each.

Mortlach produced high quality Highland malt with "quite old-fashioned means". A total of 24 men were employed to produce 8 000 gallons per week. Production was bigger than at the Invergordon distilleries, as Glen-Mhor and Glen Albyn managed only 2 500-3 000 gallons per week each. Distillation was carried out from September to end of May and the spring production was considered to be of the best quality. Mostly foreign barley was used and floor malted on site. Two kilns were used to dry malt for 50 hours in up to 77C after 9 days of germination. About 18 kg peat for every 120 kg of coal was used in kilning. Fermentation time in seven 60 000 gallon washbacks varied between 46-56 hours. After each fermentation the washbacks were washed with lime and peat was burned on the bottom of the washback to avoid bacterial contamination. The spirit was double distilled (no mention of the Wee Witchie or even partial triple distillation) to a very high proof of 45 over proof (82,8% abv) and reduced to standard 63,4% before maturation. Rummagers for wash still and direct firing with coal for both stills were used.

Thorbjörnson calculated that the blending and maturation was cheaper in big English warehouses compared to the Swedish Reymersholm or Slottet warehouses. He also thought that the flavours came mostly from the malt whiskies and therefore the malt content of the Swedish blends (Crown Blend and Black Label) should be increased. On the other hand Scotch grain whisky could be replaced with cheaper domestic neutral potato spirit to cut costs. He also made a a costs-analysis for building a Swedish malt distillery with a 500 000 litres capacity per 6 months, which apparently never came to be.

References and further reading:
Kansallisarkisto, Helsinki. http://www.arkisto.fi/en/the-national-archives-service/arkistolaitoksen-vaiheet-2

Koch B. Från idé till produkt. Svenska Uppfinnarföreningen, 1963.

Morrice, P. Schweppes guide to Scotch. Alphabooks 1983
Spiller, B. Cardhu. John Walker & Sons, 1985.

Sulphur

noreply@blogger.com (Teemu Strengell) — Sun, 05 Jan 2014 11:33:00 +0000

Sulphur candle

Sulphury notes are a controversial part of whisky aroma. Individual differences in perceiving the sulphury flavours seem to be great and easily arguable. Sulphur in its natural S8-form is quite stable with an odor of matchsticks. Most organic sulphur compounds however have usually very low perception tresholds and pungent odors. Organic sulphur compounds have been associated with meaty, burnt, rubbery, rotten aromas, but also some unexpected aromas such as grapefruit. Often low levels of sulphur are associated with mature, rancio, complex and meaty notes in whisky.

Sulphur in the whisky is mostly sourced from the aminoacids of the grains used in fermentation. The barley used in the whisky production are usually spring varieties and typically very low in protein and thus low on sulphury aminoacids (cysteine, methionine), too. However the yeasts metabolise the available aminoacids and in the process produce a variety of organic sulphur compounds. Typical byproduct of anaerobic sulphur metabolism is hydrogen sulphide (H2S), which has a strong unpleasant odor of rotten eggs and can further metabolise into thiols and other organic sulphur compounds. Excess amounts of yeast or the use of brewer's yeast or long fermentation times tend to increase the autolysis of yeasts and therefore add to the sulphur content of the wash. The lactic acid bacteriae can produce sulphury compounds, especially Lactobacillus brevis tends to impart a sulphury aroma.

Some sulphur is used during the kilning process, especially if peat is used to dry the grains. The anaerobic bacteriae in a peat bog produce sulphury compounds and obnoxious nitrosamines and by burning some sulphur with the peat the off-notes (and toxins) can be converted mainly to sulphur oxides, which do not spoil the grain.

The copper used in the distillation stills reduces the sulphury content of the whisky most likely by acting as a catalyst in processes resulting in insoluble copper sulphates. On the other hand copper has been associated with an increase in some sulphur compounds in the spirit, such as dimethylsulphate (DMS). Low copper contact (small/squat stills), fast distillation and high temperatures increase sulphury notes on new make spirit. Direct heating probably increases sulphury notes as there is bound to be some burning of grains at the bottom of the still and temperature variations between different parts of the still.

Cask maturation significantly reduces the amount of most sulphur compounds in the whisky, even so that in a recent study all of the dimethyl sulphide (DMS), 3-methylthiolpropylacetate, dihydro-2-methyl-3(2H)-thiophene and ethyl-3-methylthiol-propanoate had disappered after 3 years of oak maturation. Most organic sulphur compounds such as DMS decrease gradually during aging. This is most likely due to evaporation and to a lesser degree to oxidation or reactions with the carbon layer of the charred cask.

Key sulphur compounds in new-make spirits and single malt whiskies (Masuda & Nishimura 1982)

The individual perception of different sulphury compounds appears to be very different. As experienced tasters rated different sulphur compounds (in a study by Jack FR et al 2008), there was considerable variation between individuals and compound.

Sulphury character of different sulphur compounds, modified from Jack et al 2008

The most perceived MMFDS and 2-thiophene-cis-aldehyde, 4-methyl-thiazole, 4-methyl-5-vinyl-thiazole as sulphury and the mix of all was statistically the most sulphury of them all. At least one taster did rate the sulphury taste less than 1 out of 10 for all but two compounds. Several tasters were non-tasters for some compounds that the others rated highly sulphury. It is to be noted that all but one tasters rated one individual compound more sulphury than the mix of all, so the sulphury taste is not an add-on characteristic but rather a combination. For example 2-pentyl furan distictively suppresses the sulphury character of DMTS, just like salt suppresses a bitter taste (just try a tiny amount of salt in your coffee).

Sulphury character of different sulphur compounds, modified from Jack et al 2008

However, there has been controversy about sulphury casks in the whisky industry. Especially Jim Murray, the author of The Whisky Bible has been worried about sherry cask-derived sulphur-taints. Sulphur is widely used in wine industry to prevent bacterial growth in must and to improve the stability of wine. It is usually used in the form of sulphur dioxide, usually soluted in to a liquid form for ease of use. Sulphur dioxide acts as an antioxidant and antibacterial agent in wines. Excess sulphur dioxide content may intensify some allergic reaction and impart off-notes into wine. Sulphur candles or brimstone sticks have been used to preserve casked wine and to prevent bacterial contamination of casks stored empty.

Fumigation of casks with sulphur has been used probably from the Roman era. The use of sulphur matches and candles for preserving wines and other perishables was common in late 18th century Europe. Wine writer André Jullien describes the fumigation of wine casks in 1825:

"Fumigating wines is impregnating them with sulphurous vapours, obtained by the burning of brimstone matches... aromatics are often mixed with the brimstone... the Strasbourg [violet scented matches] are to be preferred for wine... When old wine runs clear, it is sufficient to burn a bit of match in the cask you are going to fill. To hasten the fermentation of new wine, burn several matches and shake the wine in the vapour... Many vineyards produce wines of a sulphurous taste, which goes off in time" (as cask maturation/storing was common at the time). This practice reduced the oxygen in the cask and prevented lactic bacterial brettanomyces contamination, therefore enhancing the stability and quality of wine.

Sulphur burners are still used
by amateur winemakers.

There are many references from the 1700s and the 1800s describing different cask sulphuring methods. Usually sulphur was introduced into the cask through the bunghole in a wire containing a linen cloth, which had been coated with sulphur. The cloth was burned and the bung closed, resulting in oxygen-deprived cask with some sulphur dioxide and some sulphur trioxide gasses. A fresh cask usually used first for fermentation was considered quite clean, so they were only slightly or not at all sulphured. Sulphur dusting of the vines was used as a cure against oidium (powdery mildew), the first of the fungal diseases from America, in the 1850s.

The effects of sulphur in casks were not completely understood and in 1873 there was a scandal in Britain, as Dr Thudicum wrote that the sulphuring, plastering (adding calciumcarbonite into must) and fortification of sherry was to be considered as adulteration and that the sherry wines were inferior to the French wines and probably dangerous to health. The fact that also the French were sulphuring their casks was not discussed and there were probably some trade-oriented motives behind the argument.

Different types of sulphur used in winemaking

Adding sulphur dioxide into wine has been common from at least the 1890s. It prevents bacterial and wild yeast growth and acts as an antioxidant preventing overoxidation and browning. During early 1900s some wineries used (hugely) excess sulphur dioxide in order to use bigger tanks and less strict oxygen control, but it resulted in sulphur tainted wines with overly "reduced" aromas. Sulphur dioxide content is limited by EU under 160mg/l in red wines, 210mg/l in whites and 400mg/l in sweet wines. Most wineries use concentrations below 100mg/l, but non-sulphured commercial wines are rare as they easily become oxidized. Sulphur dioxide was obtained by burning sulphur candles in the late 19th century, but since the early 1900s it has been mostly used in liquid form or as potassium metabisulphite; Californian wine expert Maynard Amerine stated already in 1970 that no burned sulphur is commonly used in wine making anymore, and there is no evidence that the major sherry cask suppliers or whisky distillers had used sulphur candles for several decades. Theoretically excess sulphur dropped from a candle might be reduced to H2S or mercaptans by yeasts producing sulphury off-notes.

Since 1986 Spain has been a member of EEC and the shipment of sherry has been made very hard by the Denominacion de Origen to encourage bottling in Spain. Bottling of sherry is done almost exclusively in Spain and full sherry casks are no longer imported. The sherry shippers had already started their own bottling plants in Spain in the early 20th century. Pedro Domecq started their bottling operations in Jerez in 1920 and Gonzalez Byass was to follow gradually during the interwar period. Sandeman bottled some of their sherries and ports in location as early as 1880, but the bottling of sherry in England by Sandeman ceased in 1969. Harvey's were the last big shipper to bottle their sherries in England, as they bought a winery in Jerez from MacKenzie in 1970 and since then have been bottling practically all of their sherries in Spain. Therefore since early 1970s many distillers have been maturing whisky in sherry casks made to order in Spain. Both American and Spanish oak casks are coopered and usually the sherry used in seasoning is oloroso, but sometimes lower quality blending sherry called raya, which resembles oloroso. Some bodegas, for example Gonzalez Byass and Pedro Romero trade their old empty solera casks, which are made exclusively of American oak and usually 80-100 years old and probably very different from a typical sherry shipping cask or a seasoned cask. Another quite popular way of producing sherry casks was to rejuvenate old exhausted cask by scraping the inner surface, toasting it again and seasoning it with sherry. Aeriation of whisky, during bottle maturation or in greater extent after the bottle has been opened, usually decreases the highly volatile sulphury notes.

In conclusion, there is good and bad sulphur in whisky. To simply pin one or two sulphur compounds responsible of the good or the bad aromas would be an oversimplification. Similarily the origins of sulphury notes seem to be impossible to track to just one source, such as sulphury cask and there is no evidence of excess use of sulphur candles in the sherry industry during the last decades, in fact quite the opposite. More likely is that there are some bad batches distilled too fast or in too warm climate that are over-sulphury, or maybe a cask has not been properly sulphured and has been contaminated with brettanomyces.

REFERENCES AND FURTHER READING
Harrison, B et al. Impact of copper in different parts of malt whisky pot stills on new make spirit composition and aroma. J Inst Brew, 2001;117(1);106-112
Jack, FR et al. Sensory implications of modifying distillation practice in Scotch malt whisky production. In Distilled Spirits, ed Bryce JH, Piggott JR, Stewart GG. Nottingham Univ Press 2008.
Jack, FR. Understanding Scotch whisky flavour. Food Sci Tech 2003;14;28-30
Jullien, A. Wine merchant's companion and butler's manual. 1825
Labuza, T et al. Maillard reactions in chemistry, food and health. RSC 1994.
Masuda, M and Nishimura, K. Changes in volatile sulfur compounds of whisky during aging. J Food Sci 1982; 47(1); 101-5
Reaich, D. Influence of copper on malt whisky character. In Proceedings of 5th Aviemore Conference on malting, brewing & distilling. 1998
www.practicalwinery.com/janfeb09/page1.htm

http://www.smws.co.uk/your-society-adventure/article-archive/A_matter_of_taste.html

History of the column still

noreply@blogger.com (Teemu Strengell) — Thu, 01 Aug 2013 17:26:00 +0000

Coffey still

Whisky can be distilled in column or pot stills. Grain whiskies are usually distilled in the faster and more economical column stills, which produce light or almost neutral spirit opposed to the heavier malt whiskies produced usually in pot stills.

Distilling wine was invented in northern Italy during the 11th century, although the Arabs and the Alexandrians had probably used distillation before that to produce infusions and concotions, perhaps even as early as in the 1st century AD. The early stills were simple pot stills with a collection pot. The apparatus was often made of clay and/or copper, sometimes partly of wood, even of leather. The shape of still was usually onion-like; wide bottom to enable efficient and fast heating and narrower head to enable condensation and collection. Some kind of worm was used from the beginning, but efficient water cooling was probably invented as late as in the 18th century. The knowledge of distillation spread through Europe and Russia during the 14th and 15th centuries and malt spirits were probably distilled in Britain and Ireland at least from the late 15th century. The design of the stills remained quite constant from the 11th to the 19th century, although there were numerous experiments with different shapes. The onion pot still however remained the still of choice until the early 19th century. Heating was provided by a naked flame, often by wood fire in southern Europe, but more often by peat in the north and after the 17th century by coal.

Water-jacketed still was invented in 1526 by Paracelsus (alias Theophrastus Philippus Aureolus Bombastus von Hohenheim the Swiss) and it became known as the Baine Marie or balneum Mariae among the alchemists. The water bath allowed the still to be indirectly heated, thus preventing the wash from burning on the bottom of the still and allowing the distillation of pomace and other thicker washes. The risk of cracking stills, especially made of clay, was also diminished by indirect heating. The fractionating system was invented as early as 1553 by German chemist Philip Ulstadius, but it did not possess any significant advantages for spirit distillers and was used primarily by (al)chemists.

The condenser was improved by a German chemist Christian Ehrenfried Weigel in 1771. He placed the worm into a tube, which was cooled by circulating cold water. The invention was named Liebig condenser. Later an englishman William Grimble invented the tube condenser 1825 and it was later improved and distirbuted widely by the Dutch still-manufacturer Armand Savalle.

The Woulfe bottle

The evolution of the still gained pace during the early years of 19th century, especially in France. An illiterate French workman Edouard Adam from Rouen attended chemistry lectures given by professor Laurent Solimani. Adam understood that the principles of the Woulfe bottle, invented by Angelo Saluzzo and used in chemistry, might also work for alcohol distilling and in 1801 invented and patented the first still to produce alcohol in one operation. In principle, that was the first working column still, although the "column" was placed horizontally and consisted of several chambers or pots. It allowed single distillation for high alcohol spirit, more effective heat exchange and relatively simple fractioning of the spirit. Mr Adam was however not successful in commercializing his invention and several distillers, including Solimani, Bérard, Barré, Brugniére, Pistorius and Carbonel, built either direct copies or similar stills with just minor modifications. The three distilleries built by Adam were not successful and he died poor in 1807.

Nääsi distillery, late 19th century Finland.
Pistorius still on the right, Savalle still at the back

Pistorius improved the Woulfe bottle principle and patented his still in 1817. It had many properties of a modern column still; the wort was fed into the rectifying part of the system and divided by the steam rising from the lower pots into alcohols, feints and the rest was piped to be redistilled in the lower pots. The rectifying plates are unique, but quite efficient allowing good reflux but also thick worts. The Pistorius still was used in central Europe and Scandinavia throughout the 19th century.

Armagnac still

The first truly continuous still was made by Fournier, who used two columns, which were heated alternately and fitted with valves for removing the residues. Professor Solimani introduced indirect steam heating for an modified Adam still in 1814 in his own distillery. French Jean Baptiste Cellier Blumenthal invented the first practical continuous still in 1808 and patented it in 1813. Basically he combined Adam's principle of multiple distilling/rectifying chambers, the early ideas of fractionation by Ulstadius, preheating and the vertical columns and the residue removal of Fournier. The apparatus still had a pot still, but the wine was feeded straight from the top of the column while vapours rose from the pot to the vertical distilling column, which had 9 perforated rectifying plates. Thus the distilling column was cooled with wine, which was simultaneously preheated for the distillation. The first stills were built by Cellier and a Dutch sugar-trader Armand Savalle, later to become a global still-manufacturer. The patent was improved with fractionating plates and draff/residue outlets and sold to Parisian apothecary Louis-Charles Derosne in 1818, who succeeded in commercializing the product. Savalle and his family continued with the original apparatus and sold them to various distilleries around the world. Some of their stills are still in use at rum, brandy and neutral spirit distilleries. Many eau-de-vie, armagnac and bourbon distillers adopted a cross-over between column and pot stills. The wort is boiled in the pot and rectified in single column with a lot of reflux.

Savalle still in Demerara Distillery, Guyana
(www.cocktailsoldfashioned.de)

In England a version of the Cellier Blumenthal still was patented in 1815 by relatively unknown Mr. Dihl, but it did not gain commercial success at the time. In the same year James Miller patented a system for preheating the wash in the worm cooler and in 1818 Joseph Corty described a still with double pots and a Pistorius-like condesenser-reflux-system. So basically all the pieces for working continuous still were available in Britain in the late 1810s. In Ireland the big pot stills ruled, although there were some experiments made with continuous distilling. John Stein at Clonmel distillery developed a triple still, basically just three stills attached to each other and Joseph Shee of Cork had a quadruple pot still, in which the first pot acted as a steam source. In 1822 Irish Andrew Perrier patented his vertical continuous still, which strongly resembled the Fournier and Cellier Blumenthal stills and by 1823 a French immigrant, a veterinary surgeon Jean-Jacques Saintmarc build a variation of the Adam still. The Saintmarc's potato spirit was not a success in England and he advanced into Ireland in 1825 and marketed grain whisky distilled with a continuous column still, but that was considered "too pure". It was until 1828 that the first commercially successful column still was built on the British Isles as Robert Stein, a member of the Stein-Haig distilling family, patented his column still. It had three preheaters and steam boiled in a separate vessel was used to heat the wash, which was intermittently sprayed by pistons into a series of chambers. The chambers were divided by crude cloths (probably haircloths). The cloth permeated ethanol well, but less so water and solubles, therefore acting both as a rectifier and a filter. It enabled large amounts of distillate to be produced in a single run and improved the heat economy compared to the pot stills. The process had to be stopped for discarding the excess oily residue, so it was not exactly continuous operation. Surprisingly the Steins used only malted barley in their Kirkliston distillery for several decades, despite the fact that most of the output was sold for gin manufacturers.

Aeneas Coffey (1780-1852)

The French-born Irishman Aeneas Coffey had retired from excise officers duty in 1824 and bought into Dodder Bank distillery in Dublin. He also managed the South King Street distillery (1828) and the Dock distillery (1834) in Dublin. The first Coffey stills were made of wood and iron and consisted of a single column, but copper plates and metallic columns quickly became the norm, most likely because of the better malleability and spirit quality. By the time Coffey patented his still design in 1830, he had introduced perforated copper plates for rectifying and pipes to remove the residual oils during distillation. During the 1830s the system was divided into two columns as it was easier to manufacture, it had better rectifying qualities as well as better heat economy. Numerous designs for rectifying plates were later introduced, although the most common was the bubble cap design. The Irish distillers trusted their big pot stills and only some Northern Irish distillers experimented with the Coffey stills, first in Derry by Andrew Alexander Watt's Abbey Street Distillery in 1833 and later in Belfast at Avoniel distillery (1882) , The Irish distillery, The Royal Irish distillery (the 1890s) and and at Dundalk (the 1880s?) distillery just south of the present border. As his stills were not selling in Ireland, Coffey moved his business to London. The first Scottish whisky distillery to install Coffey still was Grange in 1834 and during the next few years Inverkeithing, Bonnington and Cambus followed. Aeneas Coffey Jr tried his hand at Lewisham distillery, London in 1840, but was not successful and the Coffeys established themselves as still makers. At first the columns stills were used by rectifiers and gin distillers, but during the mid-1840s the Scottish distillers really started building Coffey stills.

Distillery	Still	Year
Kirkliston	Stein	1828
Cameron Bridge	Stein	1830
Grange	Coffey	1834
Inverkeithing	Coffey	1835
Bonnington	Coffey	1835
Cambus	Coffey	1836
Yoker	Stein	1845
Kilbagie	Coffey	1845
Port Dundas	Coffey	1845
Seggie	Coffey	1845
Glenochil	Stein	1846
Haddington	Coffey	1846
Croftanrigh	Coffey	1846
Kennyhill	Coffey	1847
Sunbury	Coffey	1849
Carsebridge	Coffey	1852
Saucel	Coffey	1855
Glenmavis	Coffey	1855
Caledonian	Coffey	1855
Bo'ness	Coffey	1876
North British	Coffey	1885

The Scottish patent still whisky distilleries founded in 19th century

The column still was much more efficient compared to the traditional pot still, producing higher proof (usually 86-95% ABV) spirit about ten times more in volume compared to medium sized pot still distillery. Since the malting, heating and maintenance costs were a fraction of those of a malt distillery, the column still grain spirit cost about 50-70% less compared to pot still malt whisky, even if the set-up costs were included. The northern Britons were not used to the light column still whisky and at the beginning large quantities were sold to rectifiers and gin distillers, who spiced the spirit and sold it as gin or imitation brandy or cognac. As shown in the figure below, the English rectifiers and distillers quickly adopted the Coffey still, but the more traditionalist Irish and Scots remained loyal to the pot still at least to some extent.

(Weir 1995)

During the latter part of the 19th century several factors caused the rise of the column still whisky. Branding and advertising became important at about the middle of the 19th century Britain. Several traders begun blending the products of different distilleries and sold them under their own labels. Blending enabled the inclusion of raw grain column still spirits into the mix and on the other hand blended whisky was easier to sell in the big English markets used to lighter non-smoky spirits. The column distillers began to control their pricing, the first price cartel was formed in 1856 and by the 1890's the century the DCL controlled all but most column distilleries and had a virtual monopoly during the 20th century. The tax reform in 1860 raised the taxation of foreign spirits and fortified wines and allowed commercial yeast manufacturing in the distilleries, which became a substantial source of revenue for the grain distillers towards the turn of the century.

REFERENCES AND FURTHER READING:
Barnard A. The whisky distilleries of the United Kingdom. Birlin ltd 1887
Forbes, RJ. Short history of the art of distillation. Brill 1948
House, J. Pride of Perth, Bell's 1976
Kaukoranta, A. Sulfiittispriiteollisuus Suomessa. Polar 1981
Kauppila, O. Rajamäen tehtaat. Painokaari 1988
Laver, J. The house of Haig, Haig 1958
Morewood S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. Longman 1838.
Nettleton, W. The manufacture of spirits. London 1893

Townsend B. Scotch missed. Angel's share 2000.
Townsend B. The lost distilleries of Ireland, Neil Wilson 1997

Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.

Weir, RB. The history of the Distillers Company 1877-1939, Oxford Univ Press 1995
http://www.cocktailsoldfashioned.de/2011/02/demerara-distillers-limited-guyana-rum/

A modern Coffey still in North British distillery

Finnish whisky

noreply@blogger.com (Teemu Strengell) — Thu, 18 Apr 2013 19:04:00 +0000

Early 20th century wine and spirit store in Turku (Marli)

Finland was occupied by Russia in 1808-1809 and the imports of all neutral spirits (paloviina) were prohibited by the Finnish senate under the new Russian order in 1809 (revised in 1859 and 1889). The imports of whisky were prohibited too, as most of the Finnish customs officers classified whisky as neutral spirit. Cognac was

One of the first Finnish whisky ads 29.5.1904

allowed and marketed at least from the 1820s, although much of it was probably coloured and/or spiced neutral spirits imported from Estonia, Germany and Sweden.

The English traders complained in 1901 that customs of Finland were not fair as imports of cognac were allowed, but not of whisky. It was until 27.5.1904 the senate declared that whisky was not a neutral spirit and the imports should be allowed. Just in the next couple of days there were over a dozen of traders advertising their whiskies in the Finnish newpapers. The first companies with big advertising budgets were Buchanan's, Dewar's and The Distillers Company Ltd (DCL) with different brands, such as King George IV, White Label, Highland Club, House of Lords and Perfection. Several Finnish wine traders advertised their own whiskies, often unbranded at the beginning of the century. Kinahan's Irish "L.L." Lord-Lieutenant Blended Whisky (without the 'e') was imported from Dublin (before its liquididation in 1910) and some unbranded American ryes and bourbons were available.

"The biggest whisky company in Scotland, DCL, importer for the courts and all countries. Owns the biggest export warehouses of only the old clarified absolutely pure and noble. Highest and the most original brand: "King George IV" gold label, next "Distillers", "King George IV" white label, "D.C.L." (pronounced Di, Si, Ell.) and "Highland Club". British favourite drink: "King George IV" gold label for courts, clubs and first class hotels."

Below is is quite an impressive piece of early Finnish whisky journalism, published in the newspaper Otava 2.6.1904, just a week after the legalization of whisky, written by "Kimmo".

(Very) Roughly translated to English (sorry, Kimmo): "... Despite these original forms of civilizations [referring to the distilling of paloviina] we have been flooded with western European civilization in the form of cognacs, wines and liqueurs. Mostly this European civilization has been French, German and partly Hungarian. Therefore no-one can claim that Finland would not be European enough. Only English civilization has been an unfamiliar and a forbidden fruit for us. We have imported machinery, cloth, many useful tools, even noble ideas and exported butter, timber and reels, but civilization in the form understandable to Ananias Piirakainen, we have not received. The English do not have
anything else than the whisky-civilization, but the Finnish government have until now counted whisky as a neutral spirit and therefore have prohibited the import, as we do have enough of our own domestic civilization of illicit distilling. But now has the change come, now have the doors of whisky-civilization been opened for us, too! According to the senate it is now allowed to import whisky and it will be handled equal to cognac in the customs. Hardly was the decision signed when the Helsinki papers were filled with big whisky adverts. In this era of electricity, whisky was probably flowing through the cables as soon as it was allowed to enter the country. But let us see now what the former forbidden fruit is! The word whisky (pronounced uiski) is derived from the gaelic words "uisge beatha", which mean the water of life. It is a spirit burnt from malted barley. It was first distilled and drunk in Ireland and Scottish Highlands only, but later it spread to England and the world. As early as in the 14th century the Irish have been said to be able to distill whisky. Just as we have many sorts of spirits, so does the whisky come in differnt sorts. The most famous are the "L.L." (Lord Liutenant) made in Dublin and "Scotch Whisky", which tastes peculiary smoky. In the Northern America whisky is mainly made of rye and corn. "Rye whisky" is made mainly of rye, "malt whisky" of bare malts and "bourbon" of corn and malted rye. In addition there is "whisky cordial", which is a liqueur made of whisky. Well, that's enough for the time."

Advert 1904

Uusi Suometar (29.5.1904) magazine knew that whisky was made with malted barley, with sometimes oats added, and that it was more expensive than cognac because of the longer maturation time and that the average proof was 53% abv.

The sales of whisky in Finland did not increase as expected. In 1904 there were only some 6000 litres of whisky imported and the next year it fell below 5000 litres. It was a tiny amount compared to the sales of other legal spirits of over 400 000 litres per year; paloviina sales were just below 200 000 litres and cognac over 100 000 litres per annum. The whisky sales increased slightly from 1908 to 1911; 6367 litres, 8568 litres, 11083 litres, 12959 litres, respectively. During the First World War 1914-1917 alcohol sales were allowed only in first class hotels and pharmacies, and as a result the Finnish consumption of alcohol per capita was the lowest in Europe. The Finnish senate passed the alcohol prohibition law in 1907 and again in 1909 and 1911. However it was not confirmed by the Russian goverment until 1917 after the Russian revolution and just before the Finnish independence in 6.12.1917 and it was until 1.6.1919 that the Finnish prohibition law took effect.

Glen Grant ad from 1932

As the alcohol prohibition was imposed, the Finnish state founded Valtion Alkoholiyhtiö Oy (State Alcohol corporation) to provide the nation with the alcohol for medical, technical and scientific purposes. Neutral grain and potato spirit was imported from Sweden and the UK. The corporation acquired the Kronan distillery in august 1919 for own production of spirit and yeast. The next year the distilleries of Tornator (Tainionkoski) and Hyvinkään Tehtaat (renamed as Rajamäki in 1923) were acquired. New distilleries were built in Enso in 1936 (lost in the WW II to USSR) and Koskenkorva in 1941. Distilleries produced both grain and potato spirits and additionally rectified sulphite spirits, which were cheap sideproducts from paper plants. The most commonly available alcohol during the prohibition was smuggled Estonian or German neutral spirit. Valtion Alkoholiliike was lead by a apothecarist I.R.Lindqvist, who apparently did not wholly support the prohibition and kept a broad selection of imported beverages available for medicinal purposes. The legal sales of strong spirits varied from 13 989 litres (1919) to 70 704 litres (1927) per annum during the prohibition 1919-1932. Most of it was probably neutral spirit and cognac (23 varieties), but at least seven different Scotch whiskies were imported. The selection included 5 malagas, 8 ports, 15 madeiras, 6 sherries, 1 marsala, 5 tokays, 6 sauternes, 8 other sweet wines, 28 reds, 21 whites and 5 champagnes, arguably sufficient selection for purely medicinal purposes.

Whiskies available for medicinal purposes in Finland 1926-1927

After the repeal of the prohibition, the state monopoly Oy Alkoholiliike Ab for alcohol production and sales was founded in 11.2.1932 (renamed as Alko in 1969 and Altia in 1999). The first shops opened 5th April 1932 at 10:00 am (5-4-3-2-1-0) . The sortiment was rather good with 156 items, including 16 blended whiskies.

Whiskies available in the Finnish Alko 5.4.1932, prices in FIM

The first whisky trade was made in a hurry during the spring of 1932. The newly founded company was not very organized and the first consignment with DCL for 5 600 cases (67 200 bottles) of whisky was signed on a small sheet of notebook in 5.3.1932. As the DCL wanted to confirm the transportation by sending a telegraph "Where is the ship?", the Finnish side responded: "Comes tomorrow - to the port of Scotland". Somehow the trade was pulled through in less than a month and the first shipment arrived just on time before the opening of the first shops in 5.4.1932. The whisky trade even got a head start as some shipments were caught up by pack ice in the Baltic sea and for example the deliveries of cognac were delayed.

Viski-Viina, product n:o 2

Later in that year one Irish (Paddy), one Canadian (Canadian Club) and one pure malt (Glen Grant) whisky were added to the selection. Viski-Viina, a matured Scotch grain whisky blended with two thirds of Finnish neutral grain spirit, was also introduced in 1932. The Finnish taste preferred the "cut" cognac Jaloviina, and so Viski-Viina was discontinued in 1941. In 1933 the Leijona Whiskies were introduced. They were Scottish (most likely DCL) whiskies bottled in Finland, aged 3, 5, 7 or 8 years and branded with one, two, three or four lions respectively. One and two lions were not popular and were discontinued in 1941, four lions was available until 1997. Kolmen Leijonan Whisky (three lions) is still for sale as a blended whisky and it was also available as a vatted malt until 2010.

Vatting tanks in Salmisaari

Alko investigated the possibility of own whisky production in 1930s and Bengt Thorbjörnson of Vin & Spritcentralen of Sweden was consulted on the subject. He advised against own whisky production and in fact against own maturation. Despite of that Alko kept importing considerable amounts of whisky in casks. A barrel of Finnish pure grain spirits was laid down in oak cask before the WW II, but it was used as a blending material for the popular Rajamäki Akvavit after the war, rather than marketed as whisky.

First real attempts to produce Finnish whisky in Alko started in the 1950s. The experiments were made in the Rajamäki distillery, which at the time had four different stills in use: two versions of the French double column Barbét still, a ten fold Savalle still and a Guillaume rectifier. Most likely the old Barbét still was used. Pyynikki brewery provided the peated barley malts and the distilling expertise of Sami Suominen, who had been studying brewing and distilling in the USA. Production was 60-70 000 litres per annum and after nine months of maturation in Alko's own imported sherry casks the whisky was considered "as good as an excellent American whiskey". For some reason the whisky did not get into market, but was rather used as a flavour component in Tähkäviina, a spiced spirit manufactured by Alko in 1960-1999. Another "own" whisky production by Alko was the Lion Blend, a retake on the unsuccessful Viski-Viina, a blend of Scottish whiskies and unmatured Finnish grain spirit, blended and bottled in Finland (1969-1990).

Whiskies for sale in Alko, 1972

Cooper in Salmisaari, 1950s

In 1973 Alko experimented with maturation of new make Scotch whisky in the Rajamäki warehouses using Alko's own oak casks. A similar sample was matured in a Scottish warehouse for comparison. After few years the Rajamäki warehouse was considered too warm and the stocks were moved to the bigger, colder and damper Salmisaari cellars. Most of this spirit (46 350 litres) was later used for the Lion Blend.

Alko's own whisky distillation started in 1975 in Rajamäki with an old spice still. The peated malts came from Lahden Polttimo maltings. Later quite substantial amounts of these peated whisky malts were exported to both Scottish and Japanese whisky distillers in the 1970s and the 1980s. Today Lahden polttimo produces malts for Teerenpeli and Macmyra under the name of Viking malt.

Malt exports from Lahden Polttimo (tons of barley)

Old spice still in Salmisaari

After some test runs the whisky production was transferred to Koskenkorva in late 1976, where the old Barbét column still was used. The trays of the column still could be set to seven different settings, all producing different spirits, much in the style of the lomond still. The barrels were acquired from Swedish Vin & Spiritcentralen at the beginning, but it is likely that Alko's own sherry casks and even oak chips were later used, too. The whisky production increased to million litres per annum in 1980 and the first commercial bottling

A diagram of a Barbét double column still

of Alko Whisky was released in 1.10.1981. The column distillation probably dimished the smokiness and the resulting spirit was quite light and woody, resembling more brandy than traditional Scottish malt whisky. The Alko Whisky was not a success among the Scotch whisky drinkers and the sales soon fell to a couple of hundred thousand bottles per annum and it was discontinued in 1994. The whisky matured for over ten years was released as Kypsytetty 10-vuotias Viski (marketed 1994-2000) and the younger surplus whisky was used in blended cocktails such as Prince Edward, Finn Cream and Vilakka. There was also a whisky bottling of Alko's fifty years anniversary presented for the employees of Alko in 5.4.1982.

Alko Whisky (1981-1994)

Viski 88 (1983-1994)

In 1982 Alko started to develop a stronger and more "Scottish" whisky, based on the success of Kolmen Leijonan Whisky (three lions), which was a Scottish blend bottled and partly matured in Finland since 1932. Viski 88 was released in 1.11.1983 and it became quite popular, being the most sold whisky in Finland during the 1980s and the the early 1990s. It was a blend of Scottish and Finnish whiskies with a total malt whisky proportion of 40-50% and matured in Finland. The name was chosen in the celebration of the founding year 1888 of the Rajamäki distillery. The label presents Väinämöinen (the leading character from Kalevala, the national epic poetry of Finland) as pictured on the wall of Vanha Ylioppilastalo (Old Student House) in Helsinki. Coincidentally, that is where the recent Uisge festival has been organised in 2012 and 2013. After the accession to the European Union in 1995 the name of Viski 88 was changed to Double Eight 88 and the production was discontinued in 2000 as the Finnish whisky ran out.

Alko 50-years anniversary bottling

Several independent Finnish whisky distillers have been starting production in the new millenium. Brewery restaurant Beer Hunter's in Pori was founded in 1998 and small batch whisky production started 8.11.2001. Holstein stills and mixture of Spanish sherry casks and new Portuguese casks are used for the Old Buck whisky. Teerenpeli beer restaurant was founded in 1995 in Tampere. Whisky production started in 2002 in pot stills and the first batch of 3yo whisky was released in 2005 and now an 8yo is available. Brewery restaurant Koulu (School) in Turku began their distilling in 2009 in Tuorla and their first ex-bourbon oak matured whisky named Sgoil has just been released as a 3yo. Hermannin Viinitila has recently distilled whisky in co-operation with the monastery of Valamo.

Alko Whisky 10yo 1994-2000

REFERENCES AND FURTHER READING:
Hahle, P. Apteekit alkoholinjakelukeskuksina kieltolain aikana. 1988
Häikiö, M. Alkon historia. Otava 2007
Kallenautio, J. Kieltolaki ja sen kumoaminen puoluepoliittisena ongelmana. Gummerus 1979
Kaukoranta, A. Sulfiittispriiteollisuus Suomessa. Polar 1981
Kauppila, O. Rajamäen tehtaat. Painokaari 1988
Kauppila, O. Viinejä ja väkeviä. Gummerus 1990
Kauppila, O. Koskenkorvan polttimo ja sen edeltäjät. Painokaari 1988
Kula, K. 25-vuotias Alko tänään. Alko 1957
Morewood, S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. 1838.
Mäntylä, I. Viinissä totuus. Otava 1998
Mäntylä, I. Suomalaisen juoppouden juuret. SKS 1985
Mäntylä, I. Suomalaisen juoppouden kasvu. SHS 1995
Peltonen, M. Kerta kiellon päälle. Tammi 1997
Peltonen, M. Remua ja ryhtiä. Gaudeamus 2002
Peltonen M, et al. Alkoholin vuosisata. SKS 2006
Pullat R&R. Viinameri. Tammi 2012
Sillanpää, M. Kansanhuollon keittoa ja tikkuviinaa. Martinpaino 1997
Simpura, J. Vapaan viinan aika. Kirjayhtymä 1982
Tuominen, U. Suomen alkoholipolitiikka 1866-1886. SHS 1979
Vehviläinen, O. Lahden Polttimo 1883-1983. Lahden Polttimo 1983
http://digi.lib.helsinki.fi/sanomalehti/secure/main.html?language=en

Pajarete and the wine treatment

noreply@blogger.com (Teemu Strengell) — Sun, 03 Mar 2013 12:15:00 +0000

The ruins of Torre Pajarete
Castillo de Matrera, Villamartin, Andalucia, Spain
Foto www.laspain.com

Originally pajarete (paxarete, paxaret, paxarette, pacharetti) meant the Paxarete vineyards of Cartusian Convent of San Hieronomo near Jerez de la Frontera, probably east towards Villamartin and Prado del Rey. The vineyards were planted with sweet grape varieties Millar and Pedro Ximénez grapes along with some Moscatel and Palomino. After phylloxera there is no evidence of the dark and sweet Millar variety. Sherry wines called abocado, vino seco and paxarete were made in the monastery. The first grapes to ripen were picked first and set on esparto grass mats to dry. Palomino (Listán) was picked last and pressed usually on the same or the following day. The harvest lasted for 1-3 weeks allowing the Millar, PX and Moscatel grapes to dry longer, usually about 10 days. As a result the early ripening grapes became raisined and produced natural sweet wine of 8-15% abv and about 300-400 g/l of residual sugar, which was often fortified with brandy de Jerez. Abocado was a dry oloroso style oxidized sherry (sometimes sweetened with Palomino Dulce) and Vino Seco (or Fino Seco) a dry fino/amontillado wine, both of which could be still referred as (dry) Paxarete wines in the 19th century. Similar sweet wines were made in Rota from dried Tinta grapes producing bitter-sweet dark Tintilla de Rota. Color de Macetilla or Mistela was an oloroso, which had been fortified before it fermented completely, leaving it sweet, in the style of port wines. Another similar product was mosto apagado, which was done by adding sweet mosto into the wine producing partially fermented sweet wine and usually used only in blending of sweeter sherry styles. Dulce was made by fermenting must from (mostly palomino) grapes in a cask that contained brandy; the higher alcohol stopped the fermentation before all the sugar was used, producing sweet high-alcohol white wine.

Pedro Ximénez grapes dried on grass mats

The sweet paxarete was valued highly in Spain, but in the early 19th century Britain sweet sherries were considered more of a ladies drink, men preferring drier fortified wines, beer and spirits. During the 1830s the sherry trade boomed the first time and in 1838 there were 43 registered shippers of sherry. Paxarete was one of the most expensive types, costing up to 7 times more than the cheapest real Jerez sherry (probably raya) and usually a bit more than a good aged amontillado or fino. Sherry trade reached its peak of the 19th century in the 1870s as the French strugled with vine diseases. At the same time the branding and marketing of wines by the shippers really began, which made it easier to blend different wines to be sold as sherry, including those from different regions. Blending wines with mosto (grape juice), brandy, sugar and colourings was very common and not just in the sherry business. As dried grapes were easier to transport, some paxarete was often made from grapes imported from other areas. Málaga and Montilla became major producers of pajarete sherry in the late 19th century.

Malaga Pajarete from 1968,
Imported by the Finnish church
for sacramental wine

During the latter part of 19th century the English taste shifted towards lighter drier wines, partly because of the taxation and the flood of French wine into the market after 1860 as the customs embargo was dropped. Paxarete was still imported regularly and it was one of the most esteemed "malmsey" wines in Victorian Britain. Sherry barrels were used for whisky maturation probably from the early 19th century and as the blending and branding became common towards the end of the century. Sherry casks, and most likely also sherry as an additive, were used to give body to especially the lighter and younger grain spirits. Oxidized and sweet sherries such as pajaretes, olorosos, rayas and cream sherries were preferred because they gave the darkest colour and an agreeable flavour.

Pajarete was not a legally defined until 1999, so some producers from for example Málaga and California were selling pajarete/paxarete wines of their own, sometimes consisting of Pedro Ximénez wine, but quite commonly of caramel coloured, sweetened, oxidized and fortified wines. A notable imitation sherry was the very affordable Hamburg sherry, which consisted of potato spirit, caramel and spices. It was was banned in 1870 due to "health reasons". Most big sherry shippers had their own paxarete, PX or dulce brands; The Brown Bang Sherry (Sandeman), Gran Orden PX (Garvey's), Pio IX (Pedro Domecq), Delage Dulce, Osborne Paxarete and MacKenzie's Pajarete Solera. Some producers turned their raya wines (lower quality olorosos) into paxarete by maturing them outside in the sunshine, producing more cooked and concentrated wine. Vino de color, arrope or sanchoco were commonly used in blending of paxarete and cream sherries. Vino de color is any wine cooked and sometimes additionally sweetened with mosto. Sancocho is very sweet and concentrated wine boiled to one third of the original volume and arrope is thick syrup boiled to one fifth of the original volume. The tradition of boiling wines into syrups probably comes from the Moors, as they did not drink wine for religious reasons.

Arrope syrup

In the USA the boiled sweet fortified wine was classified as "Spanish-type blending sherry" by law in 1949 and manufactured mostly in California spesifically and exclusively for the whisky industry. The blending sherry was often sweetened with sugar or caramel, cooked to a reduction and infused with oak chips. It was not taxed nor was it possible to sell it as wine for consumers. Málaga and Montilla became the biggest producers of PX Pajarete wines in the 20th century Europe and Chile has its own DO Valle de Huasco producing pajarete wine. Cyprus made numerous bulk imitation sherries; the popular Cyprus Cream sherry was even sweeter than the natural paxaretes, probably due to added sugar. Imitation sherries were often colored with vino de color or caramel and fortified with industrial alcohol. The imitation sherries really stormed into the British market in the 1950s mainly in the lower price segment by agressive pricing.

Pajarete from Tarragona,
made of Moscatel and Garnacha

In 1999 Pajarete became a protected wine variety of DO Málaga and defined as "wine liquor, or natural sweet wine with a total sugar content of 45-140g/l produced without the addition of syrup [arrope], being aged and amber to dark amber in colour.". The Málaga pajarete is usually be made of Moscatel, but some Pedro Ximénez is also used. The pajarete style wines from Jerez are nowadays called PX, Pedro Ximénez, Moscatel or Dulce sherries and most of them are made according to the original soleo method.

Pajarete probably evolved from high quality sweet natural dessert wine to the blended, sweet(ened) and fortified bulk wine in the early 20th century. An affordable sweet brown sherry wine was just what the Scotch distillers were looking for, as it made possible the fast rejuvenation of whisky casks and enabled faster maturation.

WP Lowrie?

William Phaup Lowrie (1831-1916) pioneered the whisky cask management in the late 19h century. Lowrie was a merchant for both Port Ellen whiskies and González Gordon sherries, a cooper and later a co-founder of Glentauchers distillery. He was supposedly the first blender to use (sherry) wine finishes for whisky and the first cooper to import American pre-cut staves for UK cooperages. The brewers had used steam washers for new casks for decades. The process was automated already in the 1870s and it was common to use salt, hydrochloride acid, bisulphate or bicarbonate soda as additives when rinsing beer casks prior to refills. WP Lowrie introduced the steam pressure treatment to whisky industry primarily to test the integrity of casks in 1888, but soon after the steam was used also to remove harsh tannins from the fresh wood and to impregnate the wood with wine.

The wine-treatment of new casks became common in early 20th century and in 1929 it was reported that all of the new casks to be used for Johnnie Walker whiskies were seasoned with approximately 35 litres of sweet dark sherry per hogshead for 6 weeks. The casks were stored in an individual warehouse and turned regularly for even distribution of sherry into the wood. After the seasoning the casks were lightly pressurised ("with 0,2kg pressure", probably per one square inch?) and after that the remaining sherry was poured out. About 20% of the casks were said to be new, all of which apparently were UK-coopered wine-treated hogsheads made from import oak staves from the US or the Baltic. Older UK-coopered puncheons and Spanish-coopered butts were still being used as refill casks at the time.

The use of wine-treatment was introduced to save coopering costs and to ensure the availability of fresh casks as the sherry shippers had already started their own bottling plants in Spain in the early 20th century and the availability of home-emptied sherry casks was insufficient for whisky industry. Pedro Domecq started their bottling operations in Jerez in 1920 and González Byass were to follow gradually during the interwar period. Despite that, only 20 percent of sherry imports were in bottles during 1926-1940. Sandeman bottled some of their sherries and ports in location as early as 1880, but the bottling of sherry in UK by Sandeman ceased in 1969. Harvey's were the last big shipper to bottle all their sherries in England, as they bought a winery in Jerez from MacKenzie in 1970 and since then have been bottling all their sherries in Spain. In 1983 most (54.4%) of the sherries exported were bottled in Spain. The markets of EEC were easier to reach from Spain than from UK, especially after the preferential trade agreement with Spain and the EEC in 1970 and Spain's accession into EEC in 1986. Bottling of sherry is nowadays done almost exclusively (96.5% in 2000) in Spain and full sherry casks are no longer imported.

Harvey's bottling hall in the 1960s

As imported sherry casks became scarce due to the second World War in the 1940s and especially due to the increased bottling of sherry in Spain during the 1960s and early 1970s, the distillers rejuvenated the exhausted casks with pajarete. According to Philp in 1989 "a typical cooperage procedure was to add 500ml Paxarete per hogshead or 1 litre per butt, pressurise at 48 kPa / 7 psig for 10 minutes and then disgorge any absorbed paxarete.". Until 1972 the DCL also coopered their own sherry casks, which were made of American oak to a size of a puncheon (~558 l), wine-treated with paxarete and then used primarily for grain whiskies before used for malt whiskies. The American ex-bourbon barrels often received the same treatment; first fill with grain whisky, then after wine-treatment refilled with malt whisky.

Whether the Scotch distillers used real natural pajarete wine or sweetened imitations or even arrope or sancocho for seasoning is not clear, most likely they were not too fussy about the right provenance or traditional production methods concerning their "blending sherry". The typical seasoning paxarete of the 1980s was rich in tannins, esters and especially acids. A chemical analysis of different sherries by Philp in 1989 indicates that paxarette used at that point was very likely boiled and/or sweetened with arrope or sancocho as it contained 3,2 times more sugars (375 g/l), 5,7 times more tannins (4,7 g/l), 3,6 times more esters (278 g/l) and 6,9 times more acids (22 g/l) than an ordinary sweetened oloroso. In comparison the current version of Harvey's Bristol Cream has only 3,1 g/l acids and 130 g/l sugars and the naturally very sweet Don Guido 20yo PX sherry from Williams & Humbert has only 4,5 g/l acids despite of whopping 400 g/l sugars.

Photo: Albert Watson

As the Spanish sherry producers shifted from the traditional cask fermentations to use of modern steel tanks, the properties of casks changed. Fermentation was thought to remove many unwanted flavours from the fresh wood, especially bitter and sulphury off-notes. A special Gomez treatment was invented in the 1960s to simulate the effects of fermentation in the cask. It consisted of steaming the cask with ammonium hydroxide steam at 55 kPa (8 psig) for 60 minutes, which stripped much of the tannins and colour from the inner surface of the cask. This produced very neutral casks suitable for especially fino sherry maturation, but when subsequently used in Scotland they tended to produce light-coloured and slow maturing whiskies. The Gomez treatment was used from about 1965, but during the 1970s most of the Scotch distillers stopped buying these casks and began ordering their own spesified casks for whisky maturation. The casks were used for fermentations and maturation of sherries in Spain before they were shipped usually as empty standing casks to Scotland. According to the distiller's order, both American (Quercus alba) and Spanish (Q.robur) oak were used, as well as fino and oloroso sherries.

According to a rumour the Scotch Whisky Association banned the use of paxarete in the late 1980s or early 1990s, but there is no official evidence of that. The Scotch Whisky Order from 1990 bans the use of additives other than water and caramel E150a, so the blending of whisky with sherry wine including pajarete was indeed banned at that point. PX sherry casks are still quite often used especially for single malt production, but the use of sherry concentrates and high pressures in rejuvenation and seasoning has apparently ceased or at least diminished greatly. Philip Hills wrote in 2000: "wine-treatment of worn-out casks has been widely used to simulate the effects of new sherry wood... a sweet dark sherry such as pedro ximenes [sic] is introduced and the cask is pressurised in order to force the potion into the wood. For many years, a potion called paxarette was used, which combined sweet dark sherry with other flavourings and colourants... the results are not impressive: whisky from a treated cask of this sort smells slightly sulphurous and sweet, but that is all. Of the lovely aromatic flavours of a true sherry-cask maturation, there is no trace.". It is likely that the wine-treatment was dropped because of the poor results rather than an SWA order. Below is a comparison of different cask types and maturation temperatures.

Philp 1989

Oloroso and raya sherries are probably the most common seasoning sherries used nowadays, seasoning times varying from months to couple of years. Cask fermentations are rarely done in the Scotch-bound casks. The sherry bodega casks used for maturation of commercial sherries in solera systems are discarded usually after 80-100 years and sometimes used for Scotch maturation after recoopering.

REFERENCES AND FURTHER READING:

Conner JM et al. Changes in wood extractives from oak cask staves through maturation of scotch malt whisky. J Sci Food Agric 1993;62;169-174
Crawfowd, A. Bristol wine trade. Historical association 1984
Glasgow Herald 27.5.1969

González Gordon M, Sherry. Cassell Ltd 1972
Halley, N. Sandeman: two hundred years of port and sherry. Granta 1990
Harrison, G. Bristol Cream. Batsford 1955
Hills, P. Appreciating whisky. Collins 2000
Hotelli- ja Ravintolamuseon arkisto, Helsinki.
Jeffs, Sherry. 1970
Lea GH, Piggott JR. Fermented beverage production 2nd ed. Kluwer Acad 2003
Morewood, S. A philosophical and statistical history of inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors.

Read J. Sherry and the sherry bodegas. Sotheby's 1988

Reid KJG et al. Understanding and enhancing cask performance. The Scotch Whisky Research Institute 2008.
Sykes WJ, Ling AR. The principles and practice of brewing. Griffin 1907
Wright HE. A handy book for brewers being a practical guide to the art of brewing and malting, embracing the conclusions of modern research which bear upon the practice of brewing. Lockwood & Son 1897

Bottle maturation (OBE)

noreply@blogger.com (Teemu Strengell) — Sat, 02 Feb 2013 18:53:00 +0000

Laphroaig 1887

Scotch whisky ages in oak wood casks for a minimum of three years, usually longer. After wood maturation it is usually diluted and colored with caramel E150a prior to bottling. After that the changes of whisky in a closed bottle are not fast or drastic, at least compared to for example the bottle maturation of wines. Some bottle maturation changes or "old bottle effects" are nevertheless possible.

The bottle maturation of wines depends mainly on the closure of the bottle. If there is enough oxygen present, for example through a porous or leaky closure, the wine becomes oxidized. If the closure tight, restricting the oxygen permeation, the wine becomes reduced. Screw caps and cork stoppers are usually the most tightest, synthetic corks are very permeable to oxygen and the permeability of natural corks is somewhere in between, although there are variations, especially among natural corks. The fastest oxidation happens in the beginning of bottle maturation as there is bound to be some residual oxygen in the wine (or spirit), the headspace between the closure and liquid and additionally the porous closures release some air into the bottle. Oxygen ingress in a screw cap sealed bottle is below 1 µL/day, a natural cork sealed bottle gets 2-6 µL/day for the first year and then 0,1-2,0 µL/day depending on the cork quality and a synthetic cork sealed bottle about 6-13 µL/d depending on the material. The main route for the air into the bottle is from between the glass and the cork. Practically all modern commercial wines are protected from excess oxidation by adding sulphur dioxide and sometimes ascorbic acid.

Oxidation affects wines

The oxidation usually decreases the amount of esters and several thiols, resulting in less citrus, grapefruit, boxtree and fruity notes. The amount of H₂S (rotten eggs, bad sulphur) increases slightly during bottle maturation, but less so in an oxidative environment. If there are sugars available in the liquid, the amount of furfural (nutty, rancio) usually increases, but furanone (strawberry, fresh pineapple) usually decreases. Unknown reactions produce notes of wet wool, toasted bread and caramel. Most phenols oxidize slowly, usually forming polyphenols, resulting in diminished astringency and probably less peaty whisky over years of bottle storage. An exeption in the phenol group is vanillin, which increases slowly independently of the oxidation/reduction state. Serious over-oxidation in wines creates vinegar and in considerable evaporation of alcohol out of spirit proof liquids.

In the absence of oxygen, the wine is reduced, forming significantly more esters (fruits), higher alcohols (floral, aetheral), abhexon (peach) and sulphur volatiles (struct flint, rubber), especially H₂S (rotten eggs), but also thiols and polythiols (petrol, kerosine), apparently from sulphates, sulphites and phenols.

Independently of the oxidation, tannins and antocyanins form bigger molecules, which stabilize the colour and usually turn reddish colours into orange, bricklike hues. Oaklactones tend to partially transform from trans- (spicy, incence) to cis-isomers (coconut, vanillin) in the bottle.

The cork stoppers act as a sorbtive material, especially if they are coated with polyethene and allowed to soak with the liquid. As a result the sulphur odors, especially H₂S and small thiols are reduced. On the other hand uncoated corkstoppers are more likely to leak H₂S and other volatiles out of the bottle. Screw caps do not have a significant effect on the H₂S. A faulty bottle closure or prolonged storage of opened bottle with a low amount of spirit left leads to evaporation of alcohol and oxidation of the spirit. In that case the filling level is likely to drop and the amount of esters, small thiols and other volatiles to diminish. Bottle breathing, ie leaving the bottle open overnight or half-empty with the cork for months, might therefore cure some sulphur taints, at the cost of reduced fruit and body.

The glass bottle itself is not completely inert. Especially alkaline high-alcohol solutions (vodka for example) increase the leaching of glass. This happens especially if the bottles are stored for a long time (months) in a humid environment before bottling, allowing water to attach to the inside of the bottle. Bottle glass is composed mainly of silica (SiO₂, 75%), sodium oxide (Na₂O, 15%), calcium oxide (CaO, 12%) and aluminum salts (2%). First, the water condensed from the humid air causes mainly sodium to leach out of the glass (a damp bottle storage before bottling increases the corrosion) and the increased alkalinity increases the leaching of silica, forming salts of silicic acids. Then ethanol in turn increases the solubility of inorganic acids. As a result a deposit is created in the bottle, it consists first of sodiumhydroxide (NaOH) and sodiumhydrosilicate (Na₂O x SiO₂), but it polymerizes into an amorphic gel-like structure (for example H₂SiO₃ + CaO SiO₃ + H₂O) consisting in average of CaO (43%), SiO₂ (43%) and Na₂O (14%). At the process also some metals from the glass structure are leached out. The glass leaching increases the pH of the spirit, for example in one study with vodka the pH increased from 8,85 upto 9,50, which is probably significant for flavour release, too. In the same study the weight of dried crystals was 0,5-2,1 mg per 0,7 litre bottle. As the surface/spirit ratio increases as the bottle size dimishes, the miniature bottles are certainly more prone to impart sediments. As whisky is more acidic than vodka, this is most likely a very slow reaction, happening in older lowgrade and/or miniature bottles during decades rather than months and especially if they have been stored for a while before bottling.

Lagavulin 1875

In a bottle of whisky, the same reactions are likely to happen, although the higher ethanol strength diminishes the oxidation, as ethanol is an oxygen scavanger itself. The oak extracts and the ethanol micelles diminish the extraction of volatiles from the spirit by increasing the surface tension. Most likely the bottle maturation of whisky is more reductive than oxidative, producing more fruity, aetheral, peachy, vanilla, petrol, rubbery and metallic notes and less phenolic, bitter spicy and citrus notes. Rancio flavours might arise from pentose sugars derived from caramel colouring and/or a very extractive charred cask. Some oxidation reactions are bound to happen between the spirit and the air of the bottle headspace, but they are hardly significant. Long chain fatty esters and glass silica can both flocculate in the bottle, especially if the whisky is not filtered and it is diluted and/or colored with caramel before bottling. Light usually increases the speed of reactions, whether reductive or oxidative. In any case, organoleptically significant changes in bottled whisky are likely to occur during decades, if at all.

REFERENCES AND FURTHER READING

Bailly S, et al. Fate of key odorants in sauternes wine through aging. J Agric Food Chem 2009;57;8557-8563

Brajkovich M, et al. Effect of screwcap and cork closures on SO2 levels and aromas in a sauvignon blanc wine. J Agric Food Chem 2005;53;10006-10011

Cutzach I, et al. Influence of storage conditions on the nformation of some volatile compounds in white fortified wines during the aging process. J Agric Food Chem 2000;48;3240-5

Cutzach I, et al. Study of the formation mechanisms of some volatile compounds during the aging of sweet fortified wines. J Agric Food Chem 1999;47;2837-2846

Collin S, et al. Main odorants in Jura flor-sherry wines. J Agric Food Chem 2012;60;380-387

de Aquino FWB, Franco DW. Formation of dextran deposits in Brazilian sugar cane spirits. J Agric Food Chem 2001;59;8249-8255

Godden P, et al. Wine bottle closures. Austr J Grape Wine Res 2008;7;64-105

Guloyan YA, Shelomentseva VF. Study of physicochemical phenomena in evaluation of chemical corrosion of glass. Glass and Ceramics 2000;57(7-8);267-271

Jantzen CM, et al. Durable glass for thounsands of years. Int J Appl Glass Sci 2010;1;38-62

Kochetkova GV, et al. The chemical resistance of decolorized glass bottles to spirits. Glass and Ceramics 1972;29(3);186-189

Lachenmeier DW, et al. Long term stability of thujuno, fenchone and pnocamphone in vintage preban absinthe. J Agric Food Chem 2009;57;2782-5

Kwiatkowski MJ, et al. The impact of closures including screw cap with three different headspace volumes on the composition colour and sensory properties of a cabernet sauvignon wine during two years' storage. Austr J Grape Wine Res 2007;13;81-94

Lavigne V, et al. Changes in the sotolon content of dry white wines during barrel and bottle aging. J Agric Food Chem 2008;56;2688-2693

Lopes P, et al. Impact of storage position on oxygen ingress through different closures into wine bottles. J Agr Food Chem 2006;54;6741-6746

Lopes P, et al. Impact of oxygen dissolved at bottling and transmitted through closures on the composition and sensory properties of a sauvignon blanc wine during bottle storage. J Agric Food Chem 2009;57;10261-10270

Lopes P, et al. Main routes of oxygen ingress through different closures into wine bottles. J Agric Food Chem 2007;55;5167-5170

Nose A, et al. Hydrogen bonding in alcoholic beverages and water-ethanol mixtures. J Agric Food Chem 2005;53;7074-7081

Refsgaard HHF, et al. Light-induced sensory and chemical changes in aromatic bitters. Zeitschrift Lebensmittel-Untersuchnung 1996;203;47-55

Schneider R, et al. Volatile compounds involved in the aroma of sweet fortified wines from Grenache Noir. J Agric Food Chem 1998;46;3230-3237

Silva MA, et al. Scalping of light volatile sulfur compounds by wine closures. J Agric Food Chem 2012;60;10952-10956

Vanbeneden N, et al. Decrease of 4-vinylguaiacol during beer aging and formation of apocynol and vanillin in beer. J Agric Food Chem 2008;56;11983-8

Alcohol strength

noreply@blogger.com (Teemu Strengell) — Sun, 20 Jan 2013 16:55:00 +0000

Scotch whisky is usually diluted before filled into casks. The usual filling strength for malt whiskies is 63,4-63,5% ABV (111 UK proof) and 68% ABV for grain whiskies. These are industry standards based probably on the history, minimizing evaporation losses and warehousing costs, but also creating an acceptable flavour profiles and uniform products for the blending industry. Bourbon and corn whiskey producers can by law fill at a maximum of 125 US proof (62,5%) and the Irish have commonly filled casks at 71%. Before bottling whisky is usually diluted to 40% or 43%.

Known unusual cask filling strengths are Aberlour 69,1% (121 UK proof), Bruichladdich (undiluted 70-72%), Port Charlotte (undiluted, probably over 70%), Glenrothes (63,5% and "some casks" undiluted about 70%) and Glen Scotia 62,5%. Bladnoch has experimented with higher and lower strengths, but apparently is now filling all the casks at 63,5%. Grain spirits are usually filled at 68%, but North British fills at 62-68% and Girvan at 74% (at least the ones going to Grant's). Most malt distilleries use 63,4-63,5% fills.Since 1848 the strength of whisky warehoused in a distillery was legally from 22 under proof (44,6%) to 25 over proof (71,4%) and the maximum strength of whisky sold out of a distillery was 111 proof, so at least the grain distillers were diluting their new make. Irish whisky was said to be warehoused at 14-16 over proof (65,1-66,3% abv) in 1808 and at the same time Scottish whisky for home consumption was taxed at 107 proof (61,1%). Illicit distillers most likely did not dilute their spirits, but the small stills and wide cuts probably did not produce much higher abv.

Ross states in 1970 that Scottish malt whisky is filled at 11-12 over proof (63,4-64% abv) and Irish pot still at 25 over proof (71,4% abv). The dilution to an uniform strength probably eased the common practice of exchanging cask between the different blenders. During the years of Scottish whisky overproduction in the late 70's and early 80's at least DCL "uncommonly" filled casks at full proof to cut cask- and warehousing costs. In the early 60's there were problems acquiring enough casks and that would probably have had the same effect on filling strengths. It is likely that dilution of malt whiskies down to 63,5% has been used at least for the most part of the 20th century. During the WW I the maximum bottling strength was temporarily (1915-16) adjusted to 35 under proof (37,2% abv). The alcoholic strength was indicated usually in Sykes proof until 1980, after that it has been replaced with alcohol per volume (abv).

Higher filling proof means savings on the casks and warehousing, but the faster alcohol evaporation and slower maturation curves favor dilution before casking. Very high proof spirits mature slower as they extract less color per absolute alcohol and especially less solids from the cask. Below 120-125 US proof (or not-so-coincidentally just below 63,5% abv?) the extraction is more even and efficient. Entry proof has an impact on the flavour profile, too. More alcohol solubles are extracted at high proofs, for example coumarins (often bitter, spicy), aromatic aldehydes (almonds, vanilla...) and terpenols (lapsang souchong, pine, resin...).

Entry proof of whisky and congener extraction (Reazin 1981)

The water solubles such as sugars are extracted better at lower proofs. On the other hand, higher proof alcohol breaks the lignin and hemicellulose a bit faster to increase the amounts of sugars in the spirit.

Extraction of sugars (Reazin 1981)

Tannins, esters and fats are extracted quite evenly despite changes in the ethanol concentration, but there are some important equilibriums and reversible reactions happening in the spirit. Simplified: esters+water <=> acids+alcohol and acetals+water <=> aldehydes+alcohol. The addition of water or evaporation of alcohol results in proportionally less esters (fruit) and acetals (flowery, aetheral) and more acids, aldehydes and higher alcohols.

Ethanol micelles (from blog.khymos.org)

On the other hand, ethanol forms micelles trapping hydrophobic compounds at over 23% abv. Addition of water opens up these ethanol micelles and releases some of these hydrophobic compounds but also increases the surface tension of the solution. The short chain esters (fruity, solventy, glue) are usually more volatile and evaporate in proportionally larger amounts than the long chain esters (fruity, soapy). The oak solubles in turn increase the surface tension especially at high ethanol concentrations, decreasing the overall evaporation.

Effect of ethanol concentration on the maturation of cognac (Cantagrel & Galy 2003)

Cutty Sark ad from 1977

It probably makes a difference whether the dilution is made prior the cask filling, just before bottling or in the glass. Theoretically, the dilution before casking might produce a sweeter, cleaner and less fruity and bitter-oaky spirit. The cognac producers usually add water or lower abv spirits just a small amount at the time, probably to avoid sudden changes in ethanol-water equilibrium. Dilution before bottling might have some dimishing effect on the sugars and some volatile off-notes such as glue and acetone, while probably increasing the proportional amount of linalool-oxides and bitter woody off-notes. Dilution in the glass, especially below 23% abv would release more of the hydrophobic aromas, such as esters with fruity, but also solventy and soapy off-notes.

References and further reading

Conner JM, et al. Release of distillate flavour compounds in Scotch malt whisky. J. Sci. Food Agric., 1999; 79; 1015–1020
Conner JM, et al. Agglomeration of ethyl esters in model spirit solutions and malt whiskies. J. Sci. Food Agric., 1994; 66; 45–53
Conner JM, et al. Interactions between ethyl esters and aroma compounds in model spirit solutions. J Agric Food Chem 1994;42;2231-4
Conner JM, et al. Contributions of distillate components to disperse phase structures in model spirit solutions. J Agric Food Chem 1998;46;1292-6

Lea GH, Piggott JR. Fermented beverage production 2nd ed. Kluwer Acad 2003.

Piggott JR, et al. The influence of non-volatile constituents on the extraction of ethyl esters from brandies. J. Sci. Food Agric., 1992; 59: 477–482

Reazin GH. Chemical mechanisms of whiskey maturation. Am J Enol Vitic 1981;32;4;283-9

Ross, J. Whisky. Routledge & Kegan Paul Books 1970

Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.Taylor AJ, Mottram DS. Flavour Science: Recent Developments. Woodhead Publishing 1996.

Triple distillation in Scotland

noreply@blogger.com (Teemu Strengell) — Sun, 18 Mar 2012 18:00:00 +0000

Auchentoshan still room

Scotch malt whisky is usually distilled twice in pot stills. There are some exceptions: Auchentoshan and Hazelburn (produced in Springbank distillery) are distilled three times. Benrinnes and Springbank use their own partial triple distillation methods and Mortlach is actually partially quadruple distilled. There have also been some with malt whiskies distilled in Coffey- Stein- or Lomond-stills and recently even a fully quadruple distilled malt spirit from Bruichladdich.

Old Irish pot still at Midleton (wordpress.com)

Triple distillation was and is used extensively in Ireland at least from the late 1800's, probably because of a mixture of malt and grain used in big pot still distillations did not give a sufficiently pure spirit in two simple distillations. In early 1800's a common method in Ireland was to divide the product of the wash distillation into strong and weak low wines and then distill them separatedly into new spirits feints and then re-using the feints from both low wine distillations in the next weak low wines distillation. This is actually modified double distillation, which could have been useful especially if the lower cut point of spirit distillation was to be kept quite high, which in turn would have enabled the production of cleaner and lighter style of spirit. During the 19th century as the Irish pot stills were becoming bigger the simple triple distillation was adopted in several Irish distilleries.

It is a common belief that Scottish Lowland distilleries were also using triple distillation at the time, but actually only four or five of the 31 lowland distilleries toured by Alfred Barnard in 1886 were using some sort of triple distillation. Note that just a few distilleries were producing whisky by only continuous Coffey or Stein stills, the 26 others producing at least some pot still lowland malt whisky. Dundashill produced double, triple and Coffey-still distilled whisky and sold them separatedly for blenders. Clydesdale and Greenock produced only triple distilled whisky as probably did Glentarras, too. Glentarras had one wash still, two spirit stills and one feints still, but there are no spesific descriptions of its distillation method, so it is possible that it was just partially triple distilled. Cameron Bridge produced mainly grain whisky, but also "Pot Still Irish" (grain and malt in pot stills?), "Silent Malt" (malt in Stein still?) and "Flavoured Malt" (malt in pot still?), and it is possible that some of these was/were triple distilled. For example Auchintoshan (now Auchentoshan) was double distilling and Rosebank most probably partially triple distilling in 1886. Hazelburn used triple distillation in Campbeltown, but there are no records of triple distillation in the Highlands or the Speyside at the time.

It is not exactly known, when Auchentoshan turned into triple distilling, nor whether in what extent Rosebank has used double, triple and partial triple distillation regimes during the 1900s. One source (Brian Townsend's Scotch Missed) claims triple distillation was used in Rosebank for decades, but according to Ulf Buxrud and the DCL archives partial triple distillation, much in the lines of Benrinnes, was used in the 20th century. Benrinnes has been using partial triple distillation probably from 1954 and Springbank apparently from the early 1900's. The old Hazelburn distillery was operational from 1837 to 1925. It is not known whether they used triple distillation from the beginning, but the spirit stills were quite unique as they had water jacketed tube condenser systems attached to the neck of the both spirit and feints stills (before the lyne arm) and then after the lyne arm the typical worm condensers of that era. These stills probably had very much reflux and consequently the spirit was probably quite light. The new Hazelburn was distilled first in 1997 at the Springbank distillery with "normal" stills.

Auchentoshan uses a simple triple distillation with a very narrow heart cut in the spirit run (82.5 to 80.0 ABV), which produces very light and aromatic whisky.

The Benrinnes distillation system is described in the picture below. Basically the weak feints from all (wash, feints and spirit still) distillations are redistilled in the low wines still and the first part of that is added to the spirit run. This probably adds to the copper contact for the feints fraction.

In Springbank every fifth wash distillation is double distilled as the other four batches undergo a triple distillation. All the feints are added to the intermediate still. The effect is probably much the same as in the Benrinnes system resulting in more copper contact for the feints.

In Mortlach one wash and spirit still produce simple double distilled malt whisky. The rest of the stills produce about 80% of double distilled spirit and 20% of quadruple distilled whisky. The amount of finished quadruple distilled whisky is probably much less as the latter part of the wash (weak feints) is much weaker in alcohol. The weak feints are distilled three times in a small still called the "Wee Witchie"; the first two distillations are blank runs and only solids are removed in between. The third distillation is fractioned in the normal way and the heart is mixed with the product of the other spirit stills. Because the Wee Witchie is small (7 880 litres compared to 17 000 litre spirit stills 2&3), squat and cooled with worm tubs as the other spirit stills, the copper contact is not substantial, but it is possible that the four distillations might change the properties of the feints fraction in other ways, such as successive heating, which might in turn alter the spirit. It is believed that the meaty aromas often noticed in Mortlach whisky are due to the Wee Witchie and the "Byzantine" distillation system, which has been in use from at least 1971.

Mortlach still room, the Wee Witchie at the back (from whiskymonitor.nl)

REFERENCES AND FURTHER READING:

Barnard A. The whisky distilleries of the United Kingdom. Birlin ltd 1887.

Buxrud U. Rare malts. Quiller Press 2006.

Morewood S. A philosophical and statistical history of the inventions and customs of ancient and modern nations in the manufacture and use of inebriating liquors. Longman 1838.

Townsend B. Scotch missed. Angel's share 2000.

Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.
Weir R. The history of the Distillers Company 1877-1939. Clarendon Press 1995.

Lactic acid bacteria

noreply@blogger.com (Teemu Strengell) — Sun, 12 Feb 2012 12:13:00 +0000

Lactic acid bacteria (LAB) are a diverse group of bacteria capable of lactic acid production. They are found for example in cheeses, yoghurts or decomposing plants. They are non-respiratory (anaerobic), but tolerate also aeriated environments and can survive high acid (pH 3-6) and high ethanol concentrations. The Lactobacillales can be divided into different genera, such as Lactobacillus, Leuconostoc, Pediococcus, Lactococcus and Streptococcus etc. Of these the Lactobacillus and in lesser extent the Pediococcus are dominant in distillery environment, although many others survive alongside them. The LAB are present in small quantities in the raw materials, especially the grain, but generally the contamination of wort with LAB comes from the distillery environment (pipes, washbacks etc) and therefore the LAB population in whisky distilleries remains quite stable and the dominant strains of LAB are practically unique in any one distillery.

The yeast dominates the early fermentation and LAB starts to grow significantly after about 36-48 hours as the yeast starts to drop out or die. At the start of the fermentation there are usually various types of LAB in the wort, but many of them die out as the ethanol concentration rises. The first LAB to grow are usually heterofermentative ie they metabolise sugars into lactate, acetate and CO2, the most common species being L.fermentum, L.paracasei and L.brevis. The homofermentative LAB, such as L.acidophilus and L.delbrueckii, producing only lactate from sugars appear later after about 70 hours of fermentation.

Microbes in whisky fermentation, MB-stained=dying cells (Priest 2004)

The heterofermenting LAB can also use pentose sugars, which the Saccharomyces cerevisiae can not ferment, so they are not necessarily competitive. The homofermenters use only hexoses and they always reduce the spirit yield a bit, although they can also use the autolysis products of the dying yeast for their metabolism. The usual amounts of LAB at the start of the fermentation (below 10^6 cells/ml) do not affect the spirit yield, but amounts greater than that could cut the yield up to 20%. The usual amount of LAB in the wort are usually 10^4 to 10^5 per millilitre and rise up to 10^9 at the end of a long fermentation.

Growth of lactic acid bacteria in whisky wort (van Beek 2000)

The effect of LAB on the flavour profile of whisky depends on the species and even the strain of the LAB. Also the availability of metabolites via yeast cell death affects the flavour profile. Probably the most important and common effect of LAB is the increase of lactic and acetic acid, which together with sufficient amount of alcohols leads to increased levels of esters. The lower pH also affects the volatility and activity of various aroma compounds during fermentation and distillation.

The yeast cell death allows the LAB to metabolise the autolysis products, for example the cell membranes containing lots of fatty acids. The LAB hydroxylate these fatty acids into gamma- and delta-lactones, especially gammadecalactone and gammadodecalactone, which produce a heavy sweet and fatty aroma also found in tropical fruits (apricot, peach). The use of brewer's yeast in the fermentation leads to faster yeast cell death and subsequently to higher levels of gammalactones with sweet and fatty notes.

The LAB can alter phenolic aromas as they can decarboxylate cinnamic acids to 4-vinyl guaiacol or 4-vinylphenol and further to 4-ethylphenol. Ferulic acid and p-coumaric acid are common cinnamic acids in malted barley and a typical distiller's yeast (DCL M) and most wild yeasts, but not most brewer's yeasts, can decarboxylate them into 4-vinylguaiacols (smoky, spicy, clove). The LAB has the same decarboxylation enzyme, but they can reduce 4-vinylguaiacol further to 4-ethylphenol (guaiacol, barn-yard, band-aid, brettanomyces), which usually softens the smoky aroma. The smoky aromas are dimished especially if the fermentation is allowed to continue longer.

Amounts of guaiacols in whisky fermentation with DCL M+LAB (Van Beek 2000)

	fruity	fatty	green	sweet	sour	sulphury	meaty
L.paracasei	+		+		+
L.plantarum	+		+		-
L.brevis	(-)	+	(-)	++		++	++
L.casei	+	+
L.fermentum	+	+	+
L.acidophilus		+	+
T.delbrueckii (wild yeast)	-	(+)	+	+	-	(-)	+/-

Some effects of LAB and wild yeast on the flavour of new-make spirit (Van beek 2002, Priest 2004, Wilson 2008)

The growth of LAB depends heavily on the cleanliness of the distillery. Most of the LAB from the raw materials die during the malting and mashing and the main source for the LAB is from the pipes and the washbacks. Steel washbacks are easier to clean and probably lead to lower and different LAB colonies in a distillery. Long fermentation times increase the LAB growth, especially after 48 hours. Some distilleries have variable fermentation times, for example shorter during the week and longer over the weekend, which tends to produce slightly different wash profiles. Below is a table about different distillery fermentation practices.

Distillery fermentation times and washback materials (Udo 2006)

Variable fermentation times (usually weekdays/weekends)

REFERENCES AND FURTHER READING:
Booysen C et al. Isolation, identification and changes in the composition of lactic acid bacteria during the malting of two different barley cultivars. Int J Food Microb 2002;76;63-73
Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Simpson KL et al. Characterization of lactobacilli from Scotch malt whisky distilleries and description of L.ferintoshensis. Microb 2001;147;1007-1016
Smit G., et al. Flavour formation of lactic acid bacteria and biochemical flavour profiling of cheese products. FEMS Microb rev 2005;29(3);591-610
Udo M. The Scottish Whisky Distilleries. Black & White 2006
van Beek S, Priest FG. Evolution of the lactic acid bacterial community during whisky fermentation. Appl Microb 2002;68(1);297-305
van Beek S, Priest FG. Decarboxylation of substituted cinnamic aceds by lactic acid bacteria isolated during malt whisky fermentation. Appl Envir microb 2000;66(12);5322-5328
Walker GM, Hughes PS (ed). Distilled spirits, new horizons: energy, environment and enlightenment. Nottingham Univ Press, 2010
Wilson NR. The effect of lactic acid bacteria on congener composition and sensory characteristics of Scotch malt whisky. Thesis Heriot-Watt Univ 2008.

Fermentation flavours

noreply@blogger.com (Teemu Strengell) — Wed, 23 Nov 2011 12:23:00 +0000

Fermenting in Loch Lomond distillery

Whisky wort fermentation produces ethanol, but also a variety of important flavours. Yeasts produce higher (fusel) alcohols and organic acids, which together form esters. Additionally ketones, sulphur compounds and phenols are formed. Whisky fermentation is quite similar to beer fermentation, but there are couple of important differences; the wort is not boiled, the distiller's yeast is usually propagated aerobically and the fermentations are usually not aeriated or temperature controlled (except the starting temperature). Unboiled wort allows the enzymes to continue their work and break down the oligosaccharides to increase the alcohol yield, but it also enables contamination with bacteriae and wild yeasts. If the yeast used is propagated aerobically, it is faster to start the fermentation and contains more sterols and fatty acids and thus the wort needs less oxidation or rousing.

Yeasts use simple sugars for their growth and energy metabolism. Simplified; when the yeast has oxygen, it produces water and CO₂ from glucose, but in anaerobic conditions it turns glucose into ethanol and CO₂ or alternatively glycerol. To reproduce, the yeast needs fatty acids, sterols and amino acids for its membranes and the organelles inside the cell. Oxygen is often needed in the production of these building materials.

When yeast is pitched into the wort, it secures its energy reserves and if there are enough nutritients, it starts to reproduce by budding. The beefing up-phase is called the lag phase, and it is shorter if the yeast has been aerobically grown as the cells are usually full of nutritients already. The budding phase is called the log phase or the exponential phase, during which yeasts reproduce usually 3-4 times increasing the cell population about ten-fold. As the cells form new organelles and cell membranes, they produce a variety of different organic acids, fats and sterols including various intermediate products, some of which leak out of the cell into the wort. After that the nutritients and oxygen fall short and the cells do not reproduce, but try to produce sufficient energy to survive from the sugars, this is called the stationary phase. As the cells start to die or drop out from the fermentation, lactic acid bacteriae start to grow on the wort producing flavours typical of their metabolism, such as lactic acid and several lactones.

Yeast growth in whisky fermentation (Ramsay & Berry 1983)

The amount of higher alcohols depends on the yeast growth; basically the more the yeast grows, the more higher alcohols are formed. Therefore aeriation of the wort, high nitrogen, and high temperature promote fusel alcohol production. Ale strains usually produce more fusel alcohols than lager strains, partly because of the higher fermentation temperatures. Fusel alcohols themselves are not a desired flavour in the wort - producing usually a sharp, solventy notes - but together with acids they form esters, which are important and desired flavour compounds in whisky as they produce various fruity and flowery notes.

Amino acid	Fusel alcohol
Leucine	Isoamyl alcohol
Valine	Isobutanol
Isoleucine	Active amyl alcohol
Phenyl	2-phenylethanol
Tyrosine	p-hydroxyphenylethanol / tyrosol
Tryptophan	Tryptophol
Methionine	Methionol

Table1. Aminoacids metabolise into different fusel alcohols

Ester formation depends on the amount of fusel alcohols and organic acids in the wort, but also on the activity of alcohol acetyltranferase enzymes (ATAase I and II), which in turn depends greatly on the yeast strain. Esters in the fermentation can be classified into two groups: The acetate esters (acetate+alcohol) and the ethyl esters (ethanol+fatty acid). The acetate esters are usually formed in greater amounts, but the ethyl esters can be very aromatic even in low concentrations. Common descriptors for the aromas of esters are listed in the table below. The short chain fatty acid esters (C6, C8) are formed early in the fermentation, the medium chain esters (C10,C12) quite evenly throughout the fermentation and the longer chain esters (C16) mostly at the cell-death phase. Increased cell growth usually results in lower levels of esters, due to lower levels of free fatty acids in the wort, as fats are used to build cell membranes. Organic acids are formed throughout the fermentation and at high levels they produce notes of vinegar, vomit and barnyard. The right proportion of fusel alcohols and free fatty acids or acetate is crucial when producing estery wort and avoiding the solventy off-notes from the excess alcohols and on the other hand the rancid aromas from the excess free fatty acids. An estery, fruity wort can be produced with warm long fermentations, high original gravities, high pitching rates with aerobically grown yeast and low nitrogen barley. Increased glucose levels tend to produce more short chain esters, for example isoamyl acetate with a typical banana aroma. High fermentation temperatures usually produce more acetate esters with mainly fruity aromas, but also medium-long chain ethyl esters, which can give an oily and waxy texture to the flavour.

Ester Name	Odor or occurrence
Allyl hexanoate	pineapple
Benzyl acetate	pear, strawberry, jasmine
Bornyl acetate	pine
Butyl butyrate	pineapple
Ethyl acetate	nail polish remover, model paint, model airplane glue
Ethyl butyrate	banana, pineapple, strawberry
Ethyl hexanoate	pineapple, waxy-green banana
Ethyl cinnamate	cinnamon
Ethyl formate	lemon, rum, strawberry
Ethyl heptanoate	apricot, cherry, grape, raspberry
Ethyl isovalerate	apple
Ethyl lactate	butter, cream
Ethyl nonanoate	grape
Ethyl pentanoate	apple
Geranyl acetate	geranium
Geranyl butyrate	cherry
Geranyl pentanoate	apple
Isobutyl acetate	cherry, raspberry, strawberry
Isobutyl formate	raspberry
Isoamyl acetate	pear, banana (flavoring in Pear drops)
Isopropyl acetate	fruity
Linalyl acetate	lavender, sage
Linalyl butyrate	peach
Linalyl formate	apple, peach
Methyl acetate	glue
Methyl anthranilate	grape, jasmine
Methyl benzoate	fruity, ylang ylang, feijoa
Methyl butyrate (methyl butanoate)	pineapple, apple, strawberry
Methyl cinnamate	strawberry
Methyl pentanoate (methyl valerate)	flowery
Methyl phenylacetate	honey
Methyl salicylate (oil of wintergreen)	Modern root beer, wintergreen
Nonyl caprylate	orange
Octyl acetate	fruity-orange
Octyl butyrate	parsnip
Amyl acetate (pentyl acetate)	apple, banana
Pentyl butyrate (amyl butyrate)	apricot, pear, pineapple
Pentyl hexanoate (amyl caproate)	apple, pineapple
Pentyl pentanoate (amyl valerate)	apple
Propyl acetate	pear
Propyl hexanoate	blackberry, pineapple, cheese, wine
Propyl isobutyrate	rum
Terpenyl butyrate	cherry

Table2. Common esters and their aromas.

Diacetyl is an important flavour compound producing slick, buttery mouthfeel from concentrations of about 1ppm and at higher concentrations butterscotch or even cheesy flavours, and is usually considered as an off-note. It arises from the nitrogen metabolism during the exponential phase as the cells convert aminonoacids into ketones (such as diacetyl) and back to different aminoacids, but in the late stationary and the cell-death phases the cells use ketones in their metabolism as the sugars are running low. Brewers and distillers usually allow a diacetyl-rest period after the active fermentation to clear the wort of excess ketones. Too short fermentation time usually results in excess diacetyl. Heating, for example during distilling, increases the formation of diacetyl from other ketones. Diacetyl is quite volatile with a boiling point of 88⁰C and very hard to remove from the spirit even with column distillation.

Sulphur mining in an active volcano, Java (from zmescience.com)

Yeast metabolism produces many sulphur compounds, mostly sulphur dioxide (SO₂, burnt matches). SO₂ is easily reduced to hydrogen sulphide (H₂S, rotten eggs), which is very volatile and easily carried out of the wort if sufficient CO₂ is formed. Slow fermentations due to for example low temperature, low pitching rate, contamination or unhealthy yeast could fail to produce enough CO₂, which leads to high levels of H₂S in the wort. Some highly aromatic sulphur compounds such as dimethylsulphide (DMS) and -trisulphide (DMTS), dimethylsulphoxide (DMSO), S-methyl methionine (SMM), dithiapenthyls (DTPOH, DTPA) and various mercaptans originate mostly from the malt, but are metabolised by yeast and their concentrations can be either elevated or decreased during fermentation. Methione and cysteine are amino acids with a sulphur chain, which can be broken down during cell growth and energy metabolism. Starved cells can also turn into catabolic state (autophagosytosis), in which they break down their cell organnelles (and amino acids in the process) to produce energy, and this produces excess sulphur. This is probably why anaerobically grown brewer's yeast together with distiller's yeast produces more sulphur compounds than either one used alone. Starved brewer's yeast (cropped from the brewery, not from an aerobic propagation or a lab) produces over twice as much aromatic sulphur compounds than fresh yeast of the same strain. Distiller's yeast used alone produces slightly less aromatic sulphur than a common ale yeast, probably because of its better nutritional state. The aromatic sulphur compounds are not necessarily off-notes, but are in fact needed for full-bodied and complex aromas (in the right proportions, of course).

Phenols in whisky are mostly derived from peat burnt in the maltings, but some very flavour-active phenol compounds can be produced by yeasts. Wild yeasts produce significant amounts of 4-vinyl guaiacol, which has a very potent phenolic aroma. Phenolic note has been considered an off-note in brewing and therefore the brewers have usually chosen strains that do not have a functioning gene for 4-vinyl guaiacol-production, exceptions include most hefeweisen and rauchbier yeasts and of course the lambics brewed with wild yeasts. Apparently also the commercial distiller's yeasts are lacking the "phenolic off-flavour" genes.

The picture below sums the simple reactions involved in the flavour formation during alcoholic fermentation.

Flavour formation from alcoholic fermentations. (Ramsay 1982)

References and further reading:
Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Piggott JR et al (ed). The science and technology of whiskies. Longman 1989
Querol A, Fleet GH (ed). The Yeast Handbook. Springer-Verlag Berlin 2006
Russell I (ed). Whisky, technology, production and marketing. Academic Press 2003
Walker GM, Hughes PS (ed). Distilled spirits, new horizons: energy, environment and enlightenment. Nottingham Univ Press, 2010

White C, Zainasheff J. Yeast. Brewers Association 2010

Malting in 1660s

noreply@blogger.com (Teemu Strengell) — Mon, 17 Oct 2011 15:56:00 +0000

Just found a nice article about malting barley (or bere) by Sir Robert Moray, probably written between 1660-1673 and published in 1739 as a part of The Memoirs of the Royal Society (ed. Mr Baddam). I will try to find something more recent to blog on later...

Yeasts: pedigree and properties

noreply@blogger.com (Teemu Strengell) — Fri, 30 Sep 2011 18:45:00 +0000

Compressed Mauri Pinnacle yeast (friends-of-islay.dk)

Yeasts used in beverage production mostly belong to the genus Saccharomyces. There are various species of Saccharomyces, including S.bayanus, S.cariocanus, S.cerevisiae, S.eubayanus, S.kudriavzevii, S.mikitae, S.paradoxus, S.pastorianus and in some sources S.uvarum, which is usually considered as a subspecies of S.bayanus. The nomenclature and classification of species changes almost daily and therefore is not always uniform in literature. The species can be further classified into different strains and there are currently thousands of different strains of S.cerevisiae alone. Hybridization is common between the domesticated yeasts used in alcohol production. The yeasts used in whisky industry are mostly S.cerevisiae although various secondary species have been used with it. Baker's yeast is usually S.cerevisiae, lager yeast is S.pastorianus, ale yeasts include S.cerevisiae and apparently some S.bayanus strains, rum ferments primarily on S.cerevisiae and Schizosaccharomyces (with various wild yeasts) and wine industry use mostly S.cerevisiae and/or S.bayanus together with various wild yeasts (for example Kloeckera, Saccharomycodes, Schizosaccharomyces, Hansenula, Candida, Pichia and Torulopsis).

The simple Saccharomyces yeast is a single-cell fungus, containing 16 different chromosomes and because its genome is diploid, there are 32 chromosomes containing the genome (DNA). It can reproduce by budding (producing a copy of genome and cell organs and dividing into two) or mating by spores. During the evolution of yeasts used in beverage production non- or low-spore-producing yeasts became selected, because consistency of the fermentation was preferred. Therefore the strains used in beverage industry reproduce almost exclusively by budding and therefore their genomes change mostly by spontaneos mutations and rarely by mating/breeding. In addition some yeasts produced polyploid (multiple choromosome sets) or aneuploid (multiple single choromosome or parts of it) genomes, which further improved the consistency as there are more than two copies of one chromosome in case of a harmful mutation(s) and less fertile spore production. The extra chromosomes will further split and/or integrate with the other chromosomes. Put simply: it's complicated. For example the species S.pastorianus (formerly called S.carlsbergensis, S.uvarum or S.cerevisiae var Hansen, etc) widely used in lager brewing was probably formed by hybridization of an ale yeast S.cerevisiae and a wild yeast S.eubayanus and by further mixing genetic material (parts of chromosomes) with S.bayanus, which itself is a hybrid of S.cerevisiae, S.eubayanus and S.uvarum (which is also a strain of S.bayanus species). Because of the complex choromosome structure and the restricted reproduction abilities of domesticated yeasts, systematic and predictable breeding of yeasts is very hard even with the modern genetic engineering techniques.

Proposed development of S.pastorianus and hybrids of S.bayanus (Libkind et el 2011)

Practical classification of yeast is done by its purpose (baking, ale/lager brewing, distilling) and it is common to name strains after the lab which produces it, followed by a number; for example WH301 or WL001. Various yeast labs sell probably the same (or very very similar) yeast by a different name. The yeast strains used in beverage industry can be classified further by their abilities to ferment. Important properties of an alcohol producing yeast are flocculation, attenuation, sugar utilization, ability to work in high sugar concentrations (high gravity brewing), tolerance of alcohol, temperature and various killer factors and whether they are top or bottom croppers.

Lager flocculation

Flocculation is the yeasts' ability to clump together; ale yeast flocculates on the top of the fermentation and lager yeast onto the bottom. High flocculators clump early (about 3-5 days) in the fermentation, which might lead to low attenuation, ie part of the sugars are not metabolized to alcohol. Whisky distillers usually prefer low flocculators, because flocculated yeast is more likely to stick to the heating coils or the still surface (especially when direct heated) producing burnt flavours. Low flocculators often provide better attenuation (sugar utilization) and therefore higher alcohol yields. Filtering the wash before the distillation could be an option when using medium-high flocculators, but it is not apparently used in Scotland. The "on the lees" (ie wash containing the yeast cells) distillation is considered to enhance spirit flavour in both grain and wine spirits, most likely by increased fatty acid ester and methylketone concentrations producing oily, rancio and fruity aromas

Wort contains various sugars, mostly maltose and its oligosaccharides (maltotriose, maltotetraose, maltopentaose etc), but also glucose, fructose and sucrose. The oligo- and disaccharides (glucose, fructose, sucrose, maltose) are preferred by the yeast (figure 1) and transported inside the cell by diffusion, but maltotriose utilization depends on the yeast's ability to transport maltotriose into the cell by a spesific enzyme. Effective maltotriose uptake of a whisky yeast is important for optimal alcohol yield. Apparently most whisky yeasts (and brewer's yeasts) used contain several genes for maltotriose tranport enzymes, probably result from several hybridizations and chromosomal changes.

Figure 1. Sugar utilization in all-malt wort (IBD Blue book on yeast)

Alcohol tolerance of yeast depends on the strain and the species. Most domesticated or cultured beverage yeasts tolerate over 10% ABV ethanol concentrations as most non-saccharomyces wild yeasts stop working effectively in 1-5% ABV and die in about 10% ABV as some yeasts used for industrial fuel alcohol production can go up to 23% ABV. In whisky fermentations the factor limiting the final alcohol yield is usually the amount of sugars in the wort as whisky yeast attenuation is usually very good and the primary yeasts tolerate well the 5-8% ABV of a whisky fermentation.

The killer factors are toxins that yeasts produce against other yeast strains. Strains also develop tolerance for these toxins and there are many toxins in wild yeast fermentations, too. Brewer's and distiller's yeasts are usually quite tolerant to the most common killer factors and produce some killer factors themselves, depending on the strain. Anyway a wild yeast producing a killer toxin, which is not tolerated by the primary distiller's yeast used, might ruin the whole batch by producing a stuck fermentation or an inappropriate flavour profile.

Scotch malt whisky fermentations are not usually temperature controlled (apart from the starting temperature, which is adjusted to the ambient temperature), despite practically all lager brewers and most wine producers use temperature controlled fermetors. Yeast metabolism produces lots of heat, especially when anaerobically producing alcohol. Therefore whisky yeast must tolerate different temperatures, usually from 18-20C to over 33C. Typical whisky distillery yeasts tolerate about 32-34C depending on the ethanol concentration and although some other distilling strains can cope with up to 46C (a Finnish vodka strain), most distillers yeasts produce the best alcohol yield at 20-30C. Flavour compound formation is affected quite heavily by the fermentation temperatures; higher temperature fermentations produce less esters and more higher alcohols.

The most used whisky distiller's yeast in the latter part of the 20th century was a S.cerevisiae strain called DCL M, M-strain, Quest M, Rasse M, M-1, D1 or WH301 manufactured formerly by DCL Yeast ltd and now mostly by Kerry Biosciences (Kerry Group bought Quest Ingredients in 1998). The M-strain was introduced to Scotch whisky distilleries by DCL in 1952, but a similar Rasse M was used widely in German distilleries at least from the 1930s. The name has remained the same although the properties of the strain have changed considerably from the 1930s and there most likely is some variation between different yeast manufactures despite the same name. The M-strain is a intraspecies hybrid of S.cerevisiae (as S.cerevisiae covers the former S.diastaticus species). The first Scottish pure strain whisky yeast was developed in the mid-1920s and before the WW II DCL had pure cultures of "standard" DCL-whisky yeast, DCL S.C. (probably for sugar cane fermentations) and DCL L-3 (probably a variety of the standard DCL). Whether they were used widely in distilleries is not documented, but probably they were used in DCL grain distilleries and in some malt distilleries within a reliable transport route in adjunction with a local brewer's or baker's yeast. There is some evidence that the first pure-culture distilling yeasts were being tried in Keith already in the 1870s, but apparently they were never used in larger scale.

In continental Europe pure yeast cultures were more widely used and there were spesific strains for grain/malt worts (Rasse M, Rasse XII) and rye wort (R-strain) and even a raspberry-flavour producing strain "A". Also Fleischmann and Brown-Forman in the US had developed their own distiller's strains by the 1940s. The yeast strains of European, Asian and American distillers seem to be quite different at least by their genetics (see pic below), but there is no scientific data available for differences in spirit quality or flavour. The most similar beer yeasts compared to current Scottish whisky yeasts are probably some Belgian trappist and German hefeweisen yeasts, which are low flocculators, high attenuators, very alcohol tolerant and often produce smoky-spicy aromas associated with 4-vinyl-guaiacol production typical for S.cerevisiae var diastaticus, which is considered to have contributed strongly to the development of the M-strain from the ale-type S.cerevisiae.

Neighbour-joining tree of 63
S. cerevisiae strains (Schacherer 2009)

The M-strain ruled the Scottish whisky industry from 1960s to 1980s, although many distilleries used ale brewer's and/or baker's yeasts in adjunction with it. Before WW II most distilleries propagated their yeast on site, but during 1950s the production was largely outsourced to yeast factories and breweries. The availability of cheap (used/surplus) ale yeast diminished as lager became more popular in UK and as there were claims that using brewer's yeast dimished the alcohol yield, many distilleries started using pure cultures in the 1980s. As said before, the properties of the M-strain probably changed considerably during the latter part of 20th century, primary goals being higher alcohol yields and the preservation of traditional (or neutral) flavour profile.

Cream, compressed and dried yeast

Another significant development was the development of active dry yeast (ADY or instant dry yeast IDY) during the WW II to provide longer shelf life by basically drying the yeast into small pellets rather than just a big clump. This enabled the transportation of yeast into remote locations of Scotland, too. Some Scottish malt distilleries still use dried (95% solids) or more often compressed (25-28%) bag yeast. Cream yeast (17-23% solids) was introduced in 1983 to provide easy delivery by tank trucks and automated pitching, which was important and practical for bigger plants.

The MX-strain developed in the 1990s is a bit faster fermenter and produces a very similar flavour profile compared to the M, according to the manufacturer Kerry Group. The MX is faster and more efficient especially in high gravity worts which are preferred because of the savings in heating and water costs. Another common malt whisky yeast is Pinnacle by Mauri, which is an ethanol tolerant baker's yeast (S.cerevisiae) and actually slightly faster than MX, reaching peak fermentation speed about 1 hour earlier (at 15hours of fermentation) than MX. The grain distilleries use mostly cream yeast of undisclosed strain, produced by British Fermentation Products (BFP) or Anchor Yeast. In the table below you can find information about the yeast strain used by some Scottish distillers.

M	MX	MAURI	BREWER'S + DISTILLER'S	ANCHOR/BFP
Aultmore	Bowmore 25% (+Mauri)	Aberlour	Ben Nevis (50/50)	Auchentoshan (+Mauri)
Blair Athol	Bruichladdich	Ardbeg	Balblair	Daftmill
Bruichladdich (+Mauri)	Bunnahabhain	Auchentoshan (+Anchor)	Benromach	Grain distilleries
Bunnahabhain	Craigellachie (+Mauri)	Benrinnes	Cardhu
Glengoyne (+MX)	Glengoyne(+M)	Bowmore 75% (+MX)	Glenburgie
Glen Scotia	Lagavulin (+Mauri)	Bruichladdich (+M)	Glenmorangie (5dist, 2brew)
Highland Park	Speyside (+M)	Caol Ila	Imperial
Lagavulin (+Mauri)		Craigellachie (+MX)	Jura
Macallan (+Mauri+brewers)		Dalwhinnie	Longmorn
Speyside (+MX)		Glenfiddich	Macallan (+M+Mauri)
		Lagavulin (+M)	Miltonduff
		Laphroaig	Oban
		Macallan (+M+brewers)	Speyburn
		Strathmill (+brewers)	Strathmill (+Mauri)

Yeasts used by some Scottish whisky distilleries (Udo 2006)

The use of brewer's yeast as a secondary yeast strain produces more sulphury compounds into the wash and less fatty acid esters, especially when using dry ale yeasts. As brewer's yeast attenuates or even dies earlier than distiller's strain, the use of secondary strain increases the growth of lactic acid bacteria (LAB) towards the end of fermentation, which in turn lowers the pH of the wash altering the distillation process and produces specific flavours depending on the bacteria strain. One LAB strain might produce for example vinyl-guaiacol (smoky-spicy), as another produces damascenone (floral). Practically all the LAB growth results in more esters into the new-make, especially hexanoate and octanoate and decreased ethanol yield.

Because Scottish distillers at the present time use very similar primary yeasts, the selection of the strain of distiller's yeast is a minor factor in terms of flavour profile, at least when compared with other aspects of fermentation, such as original wort gravity, fermentation time and temperature and the material and microflora of washbacks.

In the future the whisky industry is looking to develop yeast strains suitable for higher gravity worts, shorter fermentation times and better utilization of maltotetraoses and -pentoses. Hopefully the flavour issues are also considered in the process and different strains are studied for improved flavour profiles.

REFERENCES AND FURTHER READING:

Bryce JH et al (ed). Distilled spirits: Production, technology and innovation. Nottingham Univ Press 2008
Dunn B, Sherlock G. Reconstruction of the genome origins and evolution of the hybrid lager yeast S.pastorianus. Genome Res 2008;18;1610-1623

Gray WD. Studies on the alcohol tolerance of yeasts. J Bacteriol 1941;42(5);561-574

Hansen R et al. Proteomic analysis of a distilling strain of Saccharomyces cerevisiae during industrial grain fermentation. Appl Microbiol Biotech 2006;72;116-125
Landry CR et al. Ecological and evolutionary genomics of S.cerevisiae. Molec Ecol 2006;15;575-591

Libkind D et al. Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast. PNAS 2011;108;35;14539-14544
Piggott JR et al (ed). The science and technology of whiskies. Longman 1989

Pretorius IS et al. Designer Yeasts for the Fermentation Industry, Food Tech Biotech 2003;41(1);3–10

Querol A, Fleet GH (ed). The Yeast Handbook. Springer-Verlag Berlin 2006

Russell I (ed). Whisky, technology, production and marketing. Academic Press 2003
Udo M. The Scottish Whisky Distilleries. Black & White 2006

Saerens SMG et al. Genetic improvement of brewer’s yeast: current state, perspectives and limits. Appl Microbiol Biotech 2010;86;1195-1212
Schacherer J et al. Comprehensive polymorphism survey elucidates population structure of Saccharomyces cerevisiae. Nature 2009;458;342-346
Sipiczki M. Interspecies hybridization and recombination in Saccharomyces wine yeasts. FEMS Yeast 2008;8;996-1007
Suomalainen, H & Lehtonen, P. The production of aroma compounds by yeast. J Inst Brew 1978;85;149-156

Walker GM, Hughes PS (ed). Distilled spirits, new horizons: energy, environment and enlightenment. Nottingham Univ Press, 2010
White C, Zainasheff J. Yeast. Brewers Association 2010

Analysis of Michael Jackson's tasting notes

noreply@blogger.com (Teemu Strengell) — Tue, 30 Aug 2011 09:51:00 +0000

Michael Jackson

Michael Jackson (27.3.1942-30.8.2007) was the most influential beer and whisky writer of his time. He pioneered the writing of whisky tasting notes and also wrote many ground-breaking books on whisky manufacture and drinking culture. In the first edition of his most famous book, The Malt Whisky Companion (1989), he assessed 250 whiskies from 120 distilleries, a huge effort at the time. Based on his work Lapointe and Legendre (1994) studied the similarity of different whiskies. A total of 68 descriptors used five or more times in the book for describing basic malt whiskies aged circa 10 years were included in a matrix analysis to produce the dendrogram below to examine the similarities of different distilleries. Colour, nose, body, palate and finish descriptors were included. Some of the connections are quite expected, but for an average Scotch enthusiasist some are at the first glance somewhat compelling. That is probably because the descriptors are not scaled in any way and therefore the smoky notes in for example Aberfeldy and Glenugie are statistically just as strong as the smoky notes in Laphroaig. Also the amount of colouring, the cask-types and the maturation time of whiskies compared vary considerably. Anyway, despite these shortcomings, there is a highly significant correlation between the tasting notes and the geographic locations of the distilleries, especially in the 12 subgroups named from A to L. IMHO the dendrogram works pretty well in terms of grouping different styles of Scotch whiskies as well and at least is an eye-opener for some unpredicted similarities.

Lapointe 1994

The most common descriptors for each group are listed in the table below:

	color	nose	body	palate	finish
A	full gold	fruity, salty	medium	oily, salty, sherry	dry
B	amber	sweet, sherry	medium, smooth	dry, sweet	long
C	pale gold	sweet, salty	medium to full, oily	sweet, spicy	big, long, spicy
D	pale gold	fruity, grassy	oily	sweet, fruity	sweet, quick
E	pale wyne, gold	fruity, peaty	light	sweet, spicy	fruity
F	gold	aromatic	medium, smooth, light	sweet	sweet
G	gold, full gold	grassy	smooth, light	grassy	dry
H	white wyne, pale	sweet	smooth, light	sweet, dry, fruity, smoky	dry, light
I	gold, full gold	dry, peaty	medium, light, firm	dry, smoky, sweet	salty
J	full gold	dry, peaty, sherry	light to medium, round	sweet	dry
K	gold, full gold	sweet, dry, peaty	medium to full	sweet, dry	dry, long
L	full gold	aromatic, peaty	medium	sweet, smoky	smoky

...and the best whiskies of each subgroup are listed here:

	average	best in basic malts	pts	best in book (1st ed)	pts
A	75,3	Laphroaig 10	86	Laphroaig 15	89
B	80,0	Highland Park 12	90	Macallan 25	95
C	78,5	Talisker 10	90	Talisker 10	90
D	69,5	Auchentoshan 10	85	Auchentoshan 18	86
E	74,8	Bladnoch 8	85	Bladnoch GM1975	86
F	76,5	Springbank Cad15	88	Springbank Cad21	92
G	79,1	Cragganmore 12	90	Cragganmore 12	90
H	69,2	Bruichladdich 10	76	Glenfiddich 30	86
I	79,9	Longrow 14	90	Lagavulin 16	95
J	72,8	Linkwood 12	83	Linkwood GM25	87
K	74,0	Dallas Dhu GM1971	85	Dallas Dhu GM1971	85
L	73,3	Lochnagar 12	80	Lochnagar NAS	83

An interesting fact in MJ's tasting notes is that there is a significant correlation between colour, body, palate and nose, but the finish notes do not correlate with the classification derived from the other descriptions. As expected the correlation between the nose and the palate is extremely strong, but there is also a very strong correlation between the colour and the body (texture) of whisky, which might support the hypothesis that added caramel colouring affects the body (or mouthfeel) of whiskies.

Legendre 2004

REFERENCES AND FURTHER READING:

Jackson M: The whole bibliography.

Lapointe FJ, Legendre P. A classification of pure malt Scotch whiskies. Appl Statist 1994;43;1;237-257

Legendre P, Lapointe FJ. Assessing congruence among distance matrices: single-malt Scotch whiskies revisited. Aust N Z J Stat 2004;46;615-629

Mantel N. The detection of disease clustering and a generalized regression approach. Cancer Res 1967;27;209-220

Sokal RR, Rohlf FJ. The comparison of dendrograms by objective methods. Taxon, 1962;11;33-40

Ward JH. Hierarchical grouping to optimize an objective function. J Am Statist Ass 1963;58;236-244

Yeast in the 1800s

noreply@blogger.com (Teemu Strengell) — Fri, 12 Aug 2011 14:15:00 +0000

Pic from sandcreekbrewing.com

Yeast is a crucial element in all alcohol production. It converts sugars to alcohol and CO2 and its metabolism also produces a variety of flavour compounds. Yeast has been used in distilling probably from the beginning, although its importance was not fully appreciated until the late 19th century. Early distillers used beer yeast, wine lees and sometimes fruits or juices to improve fermentation and at least some re-use of distilling yeast has been done in the 1700s. In the process more alcohol tolerant and temperature resistant yest strains have been evolved and/or selected. Some distillers (and some wine makers) in the continental Europe used fermentation sticks, for example branches of hazel, which were used to stir the wort. In the process the stick was covered with yeast and acted as an inoculator for the next batch. During the 1700s the Scottish distillers sold considerable amounts of excess yeast from the fermentations to bakers, but also bought ale yeast from breweries.

Bass brewery fermentations, late 19th century

In the 1823 Excise Act the distillers were given substantial reductions on taxes to persuade them to apply for a legal licence. At the same time the yeast trade was handed over to brewers as the law was (at least interpreted) to prohibit the distillers to remove any excess yeast during fermentation. As the wort destined for distilling was not traditionally boiled, its contamination with bacteriae and wild yeasts was inevitable and therefore the yeast slurry at the end of the fermentation was not very healthy or pure and the re-use of distilling yeast was not popular. Porter yeast was preferred by many distillers, because it tolerated high gravity worts and temperature fluctuations and was believed to produce heavier style of spirit and better alcohol yields. Propagating yeast for several batches from starters acquired from the breweries was probably the method of choice for many distillers and the starter was replaced with fresh brewers' yeast as it contaminated or lost viability.

In the continental Europe distillers collected their excess yeast in the process and in 1847 the Vienna Process (or Mautner process) was invented to produce great amounts of yeast from corn based fermentations. Basically this was done with acidic, high gravity-high temperature brewing and top-cropping the excess yeast with nets. The yeast was further processed by partial drying with nets and starch, which improved the stability and eased the transportation.

As the yeast production of UK brewers was not sufficient for the increased bakery industry and the distillers were not allowed to sell their yeast, the British yeast industry became controlled by the Germans, French, Dutch and Belgians. Brewers' yeast produced bitter bread, because of hops, contaminant bacteriae and the properties of the yeast strains used, and therefore imported yeast was preferred in bakeries. There were various methods to remove the bitterness from the ale yeast, but they increased the cost of manufacturing, which was already much more than in the big grain distilleries. The UK Distillers used mostly domestic porter or ale yeast, although some bakers' yeast and imported yeast was also used, especially during the summer breaks of the breweries. In 1860 distillers were allowed to collect yeast of a total amount of 2,5% of the volume of wash and in 1880 this was increased to 10%, probably to diminish the role of "German yeast monopoly". Dr William S. Squire patented his efficient yeast manufacturing process in the UK and offered rights to the Distillers Company Limited (DCL) in 1881. Experimental yeast manufacturing started first in Cameron Bridge and Kirkliston grain distilleries during 1882 and in 1885 a larger scale industrial production was started in Cameron Bridge. Alfred Barnard described The Cameron Bridge Yeast House in 1887:

"Near the works, and standing in a small park, is a handsome building which we at first took for a church, but on enquiry we learned that it was the Yeast House, erected by the Company for the manufacture of French yeast, a large quantity of which finds its way to Glasgow and London, where its fine quality is much appreciated, and yields a large revenue."

The grain distillery Glenochil (DCL) did also produce yeast at the time of Barnard's visit (although probably not yet by the Squire's method): "The Company manufacture an enormous quantity of what is called German Yeast, considered superior to that manufactured on the Continent, and which commands a good price in the market."

In the Cambus distillery (DCL) there were plans to start yeast production: "Alongside the Water-wheel House entrance, across the lade, is a large building fitted up with machinery for making German Yeast, where about two tons can be produced weekly, but at that time of our visit this department was silent."

Bo'ness in Linlithgow owned by J.Calder & Co. operated according to their own methods imported from Germany and were more open about their process than the DCL: "Under the principal Tun Room is the patent Yeast House, where a large an remunerative business is carried on. Here the yeast from the fermenting backs is collected into three tanks. Afterwards these yeast skimmings are pumped into accordion shaped iron press- a German patent- containing twelve leaves or intersections, which are covered inside with linen cloth of various textures, forming separate divisions, through which the yeast is driven y great pressure. The dough-like material, which exudes from the last intersection, is then collected and passed through a fine sieve, whilst the liquid expressed or squeezed therefrom runs into tank. The yeast material left in the sieve, which looks like flour cakes, is afterwards weighed out in 7, 14, and 28 lbs, and pressed into conical bags and shipped off to England and Germany."

The DCL yeast business was not fully engaged or even appreciated in 1887, producing just over 5% of the total profits of DCL, but with its wide distiribution network the DCL gained practically a domestic monopoly over the yeast in the 1890s and the foreign imports declined from 14,2 tons to 6,5 tons in 1887-1901 and stopped completely before the WW I. In 1894 production was started in Carsebridge and Glenochil. DCL made good profits in the yeast trade (up to 35% of total profits in 1894-1895) and the trade partly helped it through the Pattison crisis at the turn of the century. In 1922 DCL had acquired all the yeast producing grain distilleries and controlled the yeast industry as German imports were down after the war.

The role of yeast in fermentation was surprisingly poorly understood until the late 1800s. Fermentation was believed to occur chemically, in another words sugars and water would turn into alcohol and CO2 in the presence of sufficient heat and air; yeast was considered as a byproduct. The Theory and Practice of Brewing by Michael Comburne (1762) describes fermentation as follows:

"The sensible internal motion of the particles of a mixture, by the continuance of this motion particles are gradually removed from their former situation, and after some visible separation, joined together in a different order and arrangement so as to constitute a newcompound...vegetable fermentation is the act of which oils and earth,naturally tenacious, by the interposition of salts and heat, are so much attenuated and divided, as to be made invisible with, and to be suspended in, an homogeneous pellucid fluid...the acid particles of the air, which insinuate temselves into the wort, act on the oils, and excite a motion and effervescence, which is the cause of the heat. As the internal motion goes on, the particles of the wort become more pungent and spiritous, become more fine and active: some of the more volatile ones fly off, hence the dangerous vapour called gas. The pressure of external air, from the very first of its fermenting, not only occasions the particles of wort to arrange themselves in their due order, but also by the weight and action of that element, grinds and reduces them into smaller parts. That this operation persists even after the liquor becomes fine is evident, for every fretting is a continuance of fermentation. It would seem that the more minutely the parts are reduced, the more pungency will appear, and the easier their passage be in the human frame. Lastly, in the final state of all, the active particles being entirely evaporated, a pellicle forms on the surface, seeds deposit from the air, and a moss grows." "Yeast is needed to excite the separation and new arrangement on which the perfection of the products depends, and prevent the accidents to be apprehended from worts' disposition to ferment spontaneously through slow absorbtion of air from the atmosphere." "Yeast provides bladders of the coarser oils of wort, filled with air and ready to start the motion."

A French scientist Antoine Lavoisier described the fermentation process quite accurately in 1789 as "grape must=>carbonic acid+alcohol" and in 1815 the yield of alcohol from sugar was estimated almost precisely by Joseph Gay-Lussac. Many scientists (Christian Erxleben 1815 was probably the first) of the early 19th century proposed that yeast was a living organism and that fermentation was "of some vegetal or animal origin" and as the microscopes improved, three scientists described yeast cells almost simultaneously but independently (Cagniard-Latour, Friedrich Kützing and Theodor Schwann, 1837). Schwann wrote that

"wine fermentation must be a decomposition that occurs when sugar-fungus uses sugar and nitrogenous substances for growth, during which, those elements not so used are preferentially converted to alcohol".

Saccharomyces cerevisiae

This "vitalist" theory of fermentation was strongly opposed by chemists and it was until 1879 when Louis Pasteur confirmed and described the fermentation process by yeasts. Shortly after that in 1883 the first pure yeast culture (a lager yeast Saccharomyces carlsbergesis, later S.uvarum, S.cerevisiae and S.pastorianus) was isolated in the Carlsberg brewery by Emil Christian Hansen. At about the same time truly sterile laboratories and agar plates were introduced which made possible to isolate and transport pure yeast strains.

After these findings, the the era of biotechnology really started and in the 1900s more efficient and pure yeast strains were developed. In the UK the yeast biotechnology was slower to start as breweries were conservative about pure strains and lager brewing. The DCL started to actively to develop a pure yeast strain for (grain) whisky distilling and yeast production in 1911, as they learned that The Berlin Distillers' Association had already developed a successful strain, which they used in all their distilleries. Several cultures were grown and considered, but the first suitable strain was developed not until the mid 1920s. As the whisky industry was declining and the trade of industrial alcohol increased the emphasis was heavily on alcohol yield. More about yeast strains and their influence on brewing and flavours in the following posts...

REFERENCES AND FURTHER READING:
Barnett JA. Beginnings of microbiology and biochemistry. Microbiology 2003;149;557-567
Comburne, M. The theory and practice of brewing. Haberkorn 1762

Fitzgerald M. Industrial combination in England. Ayer publishing 1927.
Udo M. The Scottish whisky distilleries. Black&White Publishing 2006.
Weir R. The history of the Distillers Company 1877-1939. Clarendon Press 1995.
Weir R. Science marketing and foreign competition in the yeast trade 1860-1918. Business History 1991;33;4;43-67
White C. Yeast, the practical guide to beer fermentation. Brewers Association 2010.

Flavour wheels

noreply@blogger.com (Teemu Strengell) — Mon, 11 Jul 2011 09:27:00 +0000

Classification of odors is a hard task. There are no generally accepted descriptors for odors and there are no measurable and defined primary odors. Cultural differences may be enormous because the smells can be perceived, learned and memorized as objects resembling something, often an another sensation by for example sight or sound or even as feelings or memories. The olfactory sensation is processed quite roughly in the subconscious brain and therefore it is harder to concentrate on details, unlike for example sight or hearing.

Various attempts have been made to classify odors. The western method has mostly tried to describe odors by naming them after familiar objects or groups of objects (lemon, fruity, flowery, spicy etc.). The Asian cultures seem to perceive and classify smells often more aestetically or subjectively (assessed by man or god). In Indian hindu and buddhist traditions the classifications of odors were simply good/bad and even/uneven (although this might also be translated faint/strong). A hindu might further divide odors into more descriptive sweet, pungent, diffusive, compact, smooth, rough and pure wehreas a buddhist might separate root-, stalk-, branch-, leaf-, flower- and fruit-odors. Most meats are often described as bad odourants in India, especially when raw, this is probably due to the strong vegetarian culture present in India.

One of the early written western classifications was made by the Swedish botanist Carl von Linne. His odores medicamentorum (1752) lists seven primary odors: Aromaticos (aromatic), fragrantes (fragrant), ambrocacos (ambrosial, musky), alliaceos (onion, garlic), hircinos (hircine, goaty), tetros (repulsive), naufeofos (nauseous). Zweibakker (1895) added another two odors: ethereal (fruity) and empyrheumatic (burnt). Henning (1915) contructed this into a prism, representing the links between different groups. For examples of cultural variation see the odor classifications of Serer Ndut tribe from Senegal and Sua Indians of Brazil in the tables below.

Odor	Example
Urinous	Europeans,horses,dogs,cats,plants used as diuretics,squash leaves
Rotten	cadavers, pigs, ducks, camels, creeping plants
Milky/Fishy	nursing women,neighbourhood tribes,goats,cows,antelopes,jackals,fish,frogs
Acidic	spiritual beings, donkeys, tomatoes, trees, roots
Fragrant	Seret Ndut, Bambara (friendly tribe), flowers, limes, peanuts, onions

Table1. The odor classification of Serer Ndut in Senegal.

Odor	Example
Bland	adult men,small mammals,small birds,fish,innocuous plants
Pungent	old men,old women,large mammals,macaw,amphibians,medicinal plants
Strong	adult women,children,carnivorous mammals,birds,harmful plants

Table2. The odor classification of Sua Indians in Brazil.

Many odor classifications might seem quite strange for someone from a different culture (although it would be great to see some whisky tasting notes by a Serer Ndut). But as you learn that onion essence is a popular compound of perfume in Africa and consider that fish and milk probably turn sour and rancid in the heat practically instantly, maybe some logic starts to emerge. But the bottom line is that there are no really universal, constant and non-culture related descriptors or classifications for smells.

A common method of classification in the late 1900s was a wheel, basically developed from the Linné-system by adding classes and simplificated from the 3D-model of Henning to one (simple circle) or two dimensional (circle with tiers). The flavour wheels have a lot in common as they are descriptive systems constructed by people from similar cultural background (educated Europeans / Americans) and probably because many have most likely been developed from the succesful wine wheel by Ann C. Noble (1990). The wheels detailed according to their use, but basic principle is often quite similar. Most wheels concentrate on the smell, but many have at least some basic taste descriptors included although none seems to list umami; for example an Asian whisky wheel would probably be quite different providing perhaps umami, soy and more than one subcategory of spices. Trigeminal activity (camphor, burning sensation) is quite usually covered in the wheels, but mouthfeel, viscosity and texture are noted surprisingly seldom. Some wheels have apparently been made from the production point of view, such as the Dewar whisky wheel and to some extent the early version of Scotch Whisky Research Institute wheel. Probably the most detailed whisky flavour wheels used are the Revised Scotch Whisky Flavour Wheel for Industrial Purposes and the Whiskymag wheel. Below you'll find some other wheels for beer, chocolate, tequila, olive oil, cigars, cheese, bodyodor and off-odors.

Wine wheel (Ann C Noble)

The Dewar whisky wheel

SWRI wheel

SWRI revised wheel

Whiskymag wheel

Macallan wheel

Coffee wheel

Fragrance wheel by Michael Edwards

Chocolate wheel

Olive oil wheel

Cigar wheel

Comté cheese wheel

REFERENCES AND FURTHER READING:

Classen C et al. Aroma: The cultural history of smell. Routledge, 1994
Lawless HT. Exploration of fragrance categories and ambiguous odors
using multidimensional scaling and cluster analysis. Chem Senses
1989;14:349– 60
von Linné C. Dissertatio medica odores medicamentorum exhibens. 1752
McHugh J. The classification of smells and the order of senses in Indian religious traditions. Numen 2007;54;374-419

Lavender in whisky. A conspiracy of French women, British brewers, Peruvian distillers and hot condensers?

noreply@blogger.com (Teemu Strengell) — Sat, 11 Jun 2011 18:35:00 +0000

Lavender

The flowery perfumy notes in whisky have been widely discussed in various forums for years. In short, some whisky drinkers have experienced very strong off-notes of lavender soap in several whiskies. Especially the flowery notes of Bowmore and Glen Garioch distilled in the early 1980s have been noted.

Lavandula angustifolia

Lavender (Lavandula) is a genus of flowering plants common in mediterranean region. There are ~39 species of lavender; the most common are Lavandula angustifolia (English lavender, common lavender, narrow leaf lavender), Lavandula stoechas (French/Spanish lavender, topped lavender), Lavandula dentata (French lavender) and Lavendula latifolia (spike lavender, broad leaf lavender, Portuguese lavender) . To make things complicated the English lavender is not native to England but to western mediterranean; the French lavender (L.dentata) is native to Spain, Canary islands and Madeira. Most of the cultivated French lavender is either L.angustifolia or a more productive hybrid of L.angustifolia and L.latifolia called lavandin (Lavandula x intermedia or L.hybrida).

The odor active compounds in lavender essential oil are primarily terpenes and their oxygenated derivatives. The essential oil of L.angustifolia is the most appreciated, described as lavender, lime tree, coriander and flowers. Lavandin (L.x intermedia) oil is much cheaper, but the odor has more soap, camphor, turpentine, artificial fruit, fat and eucalyptus. L.latifolia essential oil is even harsher with more camphor, menthol and eucalyptus. In fact coriander essential oil is closer to L.angustifolia oil than the oil of L.latifolia. In table below are percentages of odor compounds found in typical essential oils of L.angustifolia, L.latifolia and lavandin (L.x intermedia). Linalool (aka β-linalool, linalyl alcohol, linaloyl oxide, p-linalool, allo-ocimenol, 2,6-dimethyl-2,7-octadien-6-ol, licareol, coriandrol) and its derivatives are responsible for the flowery lavender scent. Often linalool is added to lavandin oil and other perfumes to soften the odor. Up to 80% of perfumed hygiene products (soaps, shampoos, perfumes etc) contain linalool, often added as a fragrance. The odor treshold for linalool is usually very low, about 0,8-7,4 ppb, depending on the stereoisomer structure. Usually oxidation of linalool compounds adds to the odor.

	L.angustifolia	L.latifolia	L.x intermedia
linalool	31	3	20
linalyl acetate	16	4	25
camphor	3	32	11
1,8-cineol(eucalyptol)	na	39	na

Table1. Essential oil compounds from different lavenders.

Monoterpene metabolism by yeasts (King 2000)

Let's assume that linalool (and/or linalyl acetate) is responsible for the lavender aroma in some whiskies. Why would some distillates contain more linalool than others?

Linalool is produced by various plants, especially by lavender and most herbs such as mints, coriander, laurels and cinnamon. Hops used in beers (Cascade hops especially) are also quite rich in linalool and sometimes hops impart a flowery odor to finished beer, especially if the hops are added after the boiling. Many brewers yeasts also affect the metabolism of monoterpenes (see picture above). Beer is usually boiled in mashing, which diminishes the linalool content considerably via evaporation (This is probably why hopped beer on a frying pan smells of lavender, see Dave's e-pistle). However, in distillery mashing the wort is not boiled and the linalool in a distillery wort would be carried into the distillate if hopped wort was used in distillation (I know, this is just about as likely as the urban legend about scented soap used in distillation).

Another possible source for linalool in wort is yeast or fungi. Distiller's yeast does not usually produce significant amounts of linalool, but brewer's yeast (both lager and ale) and some lactic acid bacteriae (Kluyveromyces lactis) do and additionally there are some mutations of Saccharomyces that produce over ten times more linalool and geraniol than ordinary fermentation yeasts. These yeasts have been used in brandy fermentations and probably in production of aromatized wines such as sweet muscat. Whether this kind of yeast strain might have been used in one or two Scotch whisky distilleries in the 1980s is extremely unlikely, but brewer's yeast has been used in many distilleries along with the distiller's yeast. Linalool concentration of wort increases as the fermentation time gets longer. Too long fermentations with brewer's yeast would probably add considerably to the linalool content of the wort. A sporadic yeast mutation, a contaminant wild yeast strain, excessive lactic bacteria growth (due to prolonged fermentation time) or a fungal infection in wort would also produce too much linalool.

Optimal condenser cooling for maximum linalool and ethanol in Pisco distilling. Continuous line=optimal, dotted line=traditional. IAF=initial aromatic fraction of heart, SNF=second neutral fraction of heart (Osorio et al 2005)

Distillation affects the linalool concentrations of the spirit. It is possible that overheating the still and burning the wash might convert some other terpenes to linalool. The amount of reflux and condenser temperature is probably even more important. To understand a bit more about linalool and distillation we should investigate pisco brandy. Pisco is a wine brandy distilled in Peru and Chile. It is batch distilled from muscat wine in ~1500l copper stills (not too different from Scotch malt whisky stills). The pisco distillers try to produce very floral spirit with lots of monoterpenes, especially linalool, which is considered a quality marker for an aromatic high-end pisco together with geraniol and nerol. Pink muscat and muscat of alexandria grapes are very rich in linalool and therefore used as a component in the wine blend, but usually also cheaper and less fragrant muscat varieties and pedro ximénez grapes are used to increase ethanol-yield. Pisco contains about ten times more linalool than the average cognac. Ester- and aldehyde- concentrations are also quite high resulting to very fragrant, floral and fruity spirit. The distillation practice and especially the cooling of the condenser is critical in producing linalool-rich spirit; usually the heads fraction is distilled without cooling the condenser, apparently to get rid of the methanol and other high volatiles quite fast without losing much linalool. The boiling point of linalool is 199°C, but since it is poorly soluble in water, it distills quite early in the run along with the alcohols. Linalool is rich in the early stages of the heart run, decreasing slightly towards the tails. Cooling the condenser fast after the heads fraction and allowing much less cooling at the middle of the heart run produces more linalool, although towards the end of the spirit run the cooling is increased to prevent the tails (especially octanoic acid) getting into the spirit.

This might support Dave Broom's speculation about the two-part condensers not working properly in the distillation. If there was an inadequate amount of cooling water in circulation of the condenser, the cooling rate and the reflux at the first part of the heart would be fine, but later in the cut the cooling rate would drop too much. This would probably produce more linalool and other monoterpenes, but also early tails. If a distiller in this case would cut the heart early to avoid the tails in the spirit, the resulting heart fraction would probably be very rich in linalool. Alternatively, if the tails cut was made by timing the run or by the ABV% (opposed to smelling), it would probably become very feinty (and floral).

Pisco

The casks might also be to blame. Fungal infection in the caskwood might be a source for monoterpenes, probably in a winery supplying the casks, as spirit (bourbon or scotch) would likely kill most fungi. Muscat wine casks are not a likely option for excess linalool and pisco is not traditionally matured in oak.

So: IF there was some excess linalool in the wash AND IF the condensers were cooled inadequately in the latter part of the spirit run, there MIGHT be excessive linalool in the spirit producing heavy aroma of lavender. The source of linalool might be hops, an odd yeast strain, brewer's yeast used together with too long fermentation times (my guess) or a fungal infection of the wort. The two-part condensers installed in early 1980s and not working (or used) properly might account for the distillation/cooling part of the problem.

Now, please do not shoot me for this speculation as this is most certainly not science, but merely (mis?-)educated guesswork. Any criticism and conversation on this FWP-phenomenon is very welcome. And for the record: I am apparently not too sensitive to the lavender smell in the Bowmores of 1980s nor in perfumes or flowers. I do get some lavender notes in the 1980s Bowmores but nothing too offensive.

Bowmore spirit still condenser (from WhiskyStory)

REFERENCES AND FURTHER READING

Broom D. Lavender lament. 2005

Colonna-Ceccaldi, B. Use of terpene-producing yeasts in brandy production. Nottingham Univ Press 2010.

Daferera DF, et al. Characterization of essential oils from lamiaceae species by FTRS. J Agric Food Chem 2002;50;5503-5507

Da Porto C, et al. Flavour compounds of Lavandula angustifolia L. to use in food manufacturing. Food Chem 2009;112;1072-1078

Diéguez SC, et al. Approaches to spirit aroma: contribution of some aromatic compounds to the primary aroma in samples of orujo spirits. J Agric Food Chem 2003;51;7385-7390

Ferrari G et al. Determination of key odorant compounds in freshly distilled cognac using GC-O, GC-MS and sensory evaluation. J Agric Food Chem 2004;52;5670-5676

King A, Dickinson JR. Biotransformation of monoterpene alcohols by saccharomyces cerevisiae, torulaspora delbrueckii and kluyveromyces lactis. Yeast 2000;16;499-506

King A, Dickinson JR. Biotransformation of hop aroma terpenoids by ale and lager yeasts. FEMS Yeast Res 2003;3;53-62

Kishimoto T et al. Comparison of the odor-active compounds in unhopped beer and beers hopped with different hop varieties. J Agric Food Chem 2006;54;8855-8861

Lea GH, Piggott JR. Fermented beverage production 2nd ed. Kluwer Acad 2003.

Lillo M et al. Chemical markers for tracking the sensory contribution of production stages in muscat wine distillates. J Food Sci 2005;70;7;432-441

Osorio D et al. Wine distillates: practical operating recipe formulation for stills. J Agric Food Chem 2005;53;6426-6331

Piggott JR, Paterson A (ed). Understanding natural flavors. Blackie academic&professional 1994

Strehle KR et al. Quality control of commercially available essential oils by means of raman spectroscopy. J Agric Food Chem 2006;54;7020-7026

Takoi K et al. Biotransformation of hop-derived monoterpene alcohols by lager yeast and their contribution to the flavor of hopped beer. J Agric Food Chem 2010;58;5050-5058

Peat Terroir

noreply@blogger.com (Teemu Strengell) — Sun, 29 May 2011 08:01:00 +0000

Arbroath maltings

In 1800's the peat used in maltings was commonly local and the kilning was done in almost every distillery. During the latter part of 1900's and the invention of industrial malting processes the maltings have been concentrated to bigger facilities, such as Diageo's Roseisle, Glen Ord and Port Ellen, Simpson's Tweed Valley, Baird's Abroath and Inverness, Greencore's Glen Esk and Buckie and Edrington's Tamdhu. Several distillery maltings are still operational, but only a few distilleries malt all of their barley on-site (Springbank, Glen Ord, Tamdhu). The use of peat has diminished as more economical fuels have been introduced, but some peat is still used to create smoky flavoured malts. The peat used in Scotch whisky maltings is sourced mostly from the north-east of Scotland, Islay and Orkney.

Peat is formed in waterlogged lands by partial degradation of organic matter. There are some differences between peat compositions based on different climate, vegetation, bog type and cutting depth.

Peatlands can be divided into bogs, fens, marshes ja swamps. Bogs are formed by heavy rainfall (therefore called ombotrophic) and usually contain more sphagnum moss and less woody vegetation than the other peatland types, which are formed mostly by waterlogging from the ground water (minerotrophic). Fens (aka basin bogs or valley bogs) contain more sedges and grass. Marshes are treeless intermittently waterlogged areas and usually accumulate peat very slowly. Swamps are very minerotrophic and contain large amounts of wood and nutritients. Average peat contains 90% water and 10% dry matter, of which 92% is organic and 8% inorganic (practically ash). Organic matter consists mainly of residues of lignin and different carbohydrates, but there are considerable variations depending on the vegetation and the bog type. Ombotrophic peats are richer in phenols and aromatics, but due to poorer vegetation they lack carbohydrates, lignin and nitrogen. Western Scotland and the islands are especially abundant with blanket bogs. About 10% of Scotland in covered by blanket bogs and 1% by basin bogs.

Peat bog	Maltings	Location	Bog type
Glenmachrie	Laphroaig	Islay	basin
Gartbreck	Bowmore	Islay	basin
Castlehill	Port Ellen	Islay	blanket
Hobbister Hill	Highland Park	Orkney	blanket
St Fergus	various	Aberdeenshire	basin
Tomintoul	various	Speyside	basin
Machrihanish	Springbank	Campbeltown	blanket

The extraction depth is also important as the surface layers are usually rich in carbohydrates and poor in phenols and the deeper layers might have too much harmful nitrogen- and sulphur compounds due to anaerobic fungal and bacterial metabolism. On the other hand some fungi seem to produce vanillins such as acetovanilline from lignin, for some unknown reason especially so in island peats.

Location of peat bogs used in whisky production

Islay peat bogs (from left: Gartbreck, Glenmachrie, Castlehill)

It seems that the most significant factors in peaty aroma are the bog location and the cutting depth. The bog type and the vegetation play some role, but they are not that important for peaty flavour. The peats from Islay, for example, are very similar with each other as the peat from the basin bogs Glenmachrie (Laphroaig) and Gartbreck (Bowmore) cannot be identified by infrared spectroscopy.

The Castlehill peat for the Port Ellen Maltings somewhat different from the basin bog peats from Islay, probably due to different microbiology of the blanket bog and a greater amount of woody material are therefore more lignin-derivatives and carbohydrates.

Surprisingly, Hobbister Hill peat from a blanket bog is chemically more similar to the Islay basin bog peats (Gartbreck/Glenmachrie) than the blanket bog Castlehill peat. The local microbiology of peat bog might therefore have a greater impact on the peat composition, influencing both the nitrogenlevels and phenol-concentrations in the peat. Another explanation is that the bog types are overlapping, for example Hobbister Hill bog might have some basin bog properties (standing water bowls) especially in the deeper layers; this might explain the similarity of peats cut from the deeper layers of Hobbister Hill bog with the Islay basin bog peats.

Tomintoul peat is different from the Island peats; a basin bog, as expected, contains great amounts of carbohydrates, but there is also lots of sphagnum moss, which for some reason does not result in the same amounts of phenols as in the islands. It could be speculated that this is due to different climate, microbiology or variety of Sphagnum in the western islands and the mainland.

St Fergus peat is rich in woody material and therefore rich in lignin derivatives, especially syringyl. There is however a great amount of phenol-compounds in the St Fergus peat, although it is a basin bog and the sphagnum-content is lower than in for example Tomintoul peat. The location of St Fergus bog is closer to the sea than of Tomintoul bog. Maybe the proximity of sea results in greater amounts of phenols in peat? Explanation might be for example lesser temperature fluctuations or differences in microbiology or drainage.

There are no scientific analyses available on Machrihanish (Springbank) peat, but since it is cut from a blanket bog and located near sea in the western Scotland, it probably is closer to the Islay and Orkney peats than the mainland peat.

Some breweries use artificial smoke flavourings in their malting processes, apparently common raw materials are extracts from burnt deciduous trees, such as beech or birch. These are likely to produce more aromas from syringyl, guaiacol and carbohydrates resulting in softer but not as phenolic aroma as from peats. I don't know whether Scotch whisky industry uses smoke flavourings in their maltings, but it is not prohibited in the Scotch whisky regulations. A black alder smoked malt could be an interesting experiment (a free hint for any progressive distillers reading this).

Anyway, there clearly is a peat terroir and even some local variations in the compositions. Also the cutting depth is important and it will be interesting to see wheter the peat composition will change as the limited amounts of peat for example from Islay are utilised and either the cutting depth or the cutting location changes.

REFERENCES AND FURTHER READING:

Bozkurt S et al. Peat as a potential analogue for the long-term evolution in landfills. Earth Sci Rev 2001; 53; 95-147
Bryce JH et al (ed). Distilled spirits, production, technology and innovation. Nottingham Univ Press, 2008
Da Porto C et al. A study on the composition of distillates obtained from smoked marc. Anal Chim Acta 2006; 563; 396-400

Guillén M et al. Carbohydrate and nitrogenated compounds in liquid smoke flavorings. J Agric Food Chem 2001; 49; 2395-2403

Guillén M, Manzanos M. Study of the components of a solid smoke flavouring preparation. Food Chem 1996; 55; 3; 251-257

Guillén M, Manzanos M. Characterization of the components of a salty smoke falvouring preparation. Food Chem 1996; 58; 1-2; 97-102

Harrison B, Priest F. Composition of peats in the preparation of malt for scotch whisky production. J Agric Food Chem 2009; 57; 2385-2391

Harrison B et al. Differentation of peats used in the preparation of malt for scotch whisky production. J Inst Brew 2006; 112; 4 ; 333-339

Jefford A. Peat, smoke and spirit. Headline 2004

Jounela-Eriksson P. The aroma composition of distilled beverages and preceived aroma of whisky. Academic Press 1978

Kostyra E, Barylko-Pikielna N. Volatiles composition and flavour profile identity of smoke flavourings. Food Qual Pref 2006; 17; 85-95
Lehtonen M. Phenols in whisky. Chromatographia 1982; 16; 201-203

Russell I (ed). Whisky, technology, production and marketing. Academic Press 2003

Swan JS, Howie D. Sensory and analytical studies of regional influence on the composition of Scotch malt whisky. Institute of brewing, 1983.

Valaer P. Scotch whisky. Industr Engineer Chem 1940; 32; 7; 935-943

Walker GM, Hughes PS. Distilled spirits, new horizons: energy, environment and enlightenment. Nottingham Univ Press, 2010

Caramel E150

noreply@blogger.com (Teemu Strengell) — Sun, 17 Apr 2011 15:17:00 +0000

E150a-d

Spirit caramel (E150) is allowed as a colouring agent in Scotch whisky production. There are four different types of E150, labeled from a to d, or from class I to IV, according to the manufacturing process used. E150a (plain caramel) is "prepared by the controlled heat treatment of carbohydrates (commercially available food grade nutritive sweeteners which are the monomers glucose and fructose and/or polymers thereof, e.g., glucose syrups, sucrose, and/or invert syrups, and dextrose). To promote caramelization, acids, alkalis and salts may be employed" (not ammonium compounds or sulphites). Sulphites are allowed in the production of E150b (caustic suphite caramel), ammonium compounds are allowed in the process for E150c (ammonia caramel) and both suphites and ammonium compounds are allowed in the process for E150d (sulphite ammonia caramel). Common raw materials for caramel colourings are corn syrups, wheat, glucose syrup or sucrose. Additives may include a variety of acids, alkalis and salts. Different raw materials produce different caramels and the use of additives influences the resulting color, viscosity, ionic charge and pH and there are hundreds of different spirit caramels available from several producers.

Caramels from DD Williamson. 570 is their most used spirit caramel.

Caramel samples from Sethness. Typical spirit caramel is 0.075-0.110

Most caramel colourings are very dark in color and are usually used in tiny quantities. Fructose produces the darkest color, probably because it starts to caramellisate in 110ºC, as sucrose, glucose and galactose caramellisate in 160ºC and maltose in 180ºC. Viscosity varies, but in general low viscosity caramels are used in beverages. The ionic charge of caramel is important because of possible flocculation. For example, if negatively charged caramel is added to positively charged beverage, there will be some flocculation or even percipitation. Correctly selected caramel colouring has some emulsifying properties, in other words it helps the oils to mix with the water. In fact, the Coca Cola Company first patented the caramel colouring as an emulsifying agent, not as a colourant. Whisky and most soft drinks are negatively charged, but beer, baked goods and herbal liqueurs have usually a positive charge. E150c is positively charged and used in breweries and never in whisky. E150a has the best stability in high proof alcohols, especially when the raw material has been sucrose. Wheat and corn based syrups are widely used, but they are usually less stable in alcohol. E150a can tolerate up to 75% abv as most E150d is guaranteed to work up to 50% or 60% abv. E150b is used in the presence of tannins, especially in sherries, wines and some brandies and the residue sulphites of E150b probably also help to preserve the wine from excess oxidation. The amount of caramel varies, in spirits it is usually about 0,1-0,5% or about 1-5g/litre as in comparison some 0,4% of E150d is used in cola soft drinks, 0,01-0,3% of E150c in beers and up to 10% of E150d in (cheap) cocoa powders. EU (EFSA) recently lowered the acceptable daily intakes (ADI) for caramels; 300mg/kg/day for E150 and 100mg/kg/day for E150c, so a man weighing 80kg is allowed to consume 24g of caramel color a day. Hopefully not many of us get that from blended whisky, but probably some will get those amounts from cola and bakery stuffs.

Most producers give caramel colors a two year shelf stability guarantee, if stored in room temperature and protected from sunlight. Sunlight fades the caramel colors rapidly, in matter of weeks to months. E150a is the most resistant to fading and it fades evenly in all wavelenghts, as E150d usually fades more of the higher wavelenghts (red fades first).

Loch Dhu, mit farbstoff

The majority of single malts and virtually all the blends are coloured with E150a. According to The Scotch Whisky Regulation in 2009 only "plain caramel" (E150a) is allowed, although the EU laws permit the use of "spirit caramel", which is not exactly defined in law and can be any E150 and so at least some E150b and E150d could have been used in Scotch whiskies.

Toasting a barrel (vinography.com)

Due to the variety of raw materials and additives, the chemical structures of caramels are complex and there are lots of variations even between caramels of the same subgroup. In the production the main reaction is dehydration as water (hydrogen and oxygen) is extracted (boiled) out of the sugars. This results first to sugar monomers as polysaccharides (for example sucrose) are divided into glucose, fructose, galactose, xylose and maltose. As the heating continues, the monosaccharides lose water and react with each other producing big polymers, mainly caramelans (C₂₄H₃₆O₁₈), caramelens (C₃₆H₅₀O₂₅₎ and caramelins (C₁₂₅H₁₈₈O₈₀₎, which give the caramel most of its color. Additionally some residue sugar may be left in the product and several flavour components are produced, for example different furans, diacetyl, maltol, esters and lactones. Furans are probably the most influential flavour components in most caramels, they are formed especially from fructose or sucrose (containing fructose) in acidic encironment. They also form during the toasting of oak barrels, but the relative amounts of different furans are different as the raw material are either lignin and (hemi)cellulose in oak or simple sugars in caramel. Caramellisation of simple sugars produce less furfural (almond, walnut, grainy) and more 5-hydroxymethylfurfural (butter, musty, waxy, caramel) than caramellisation of oak (there are also significant differences between different oak species, see previous blogs). 5-HMF is not produced if sulphites or ammonium are used in the process (E150b or E150d), but is formed in large quantities in the plain caramel (E150a). 5-HMF is also used as a flavour enhancer in milkpowders, honey, juices and even cigars. Furfural acts as a reactant with various compounds in the spirit; it has some antioxidative properties that slow the oxidation reactions and help to stabilize the color from antocyanins (in especially wine), it also reacts easily with H₂S (rotten eggs, nasty sulphur) producing furfurylthiol (strong coffee), decreases the volatile sulphur compund concentrations and potentiates the odor of oaklactone (vanilla,coconut). Some other furans such as hydroxyacetylfuran (sweet), hydroxydimethylfuranone (also known as furaneol, additive in baked bread, coffee and chocolate) and dihydroxydimethylfuranone are also produced. Diacetyl imparts a buttery (butterscotch) flavour and maltol (aka E636) gives freshly baked bread aromas. Esters and lactones (here from sugar, not oak) are usually fruity. Also increased levels of E2-nonenal (cardboard, stale beer) and less hop flavour are also found in caramel coloured beers, but this possibly results from changes in fermentation process and is not studied properly in spirits.

So, caramel does affect the flavour and it is not inert in whisky, but are the quantities used in Scotch whisky industry enough to affect the overall flavour significantly? No reliable scientific fact exists, but my guess is that they probably are significant. Does caramel impair the flavour? It could, but then again in some cases caramel might even improve the taste.

References and further reading:

Abalos D et al. The use of furfural as a metabolic inhibitor for reducing the alcohol content of model wines. Eur Food Res Tech 2011;232;663-669

Blanchard L et al. Formation of furfurylthiol exhibiting a strong coffee aroma during oak barrel fermentation from furfural released by toasted staves. J Agric Food Chem 2001;49;4833-4835

Boscolo M et al. Spectrophotometric determination of caramel content in spirits aged in oak casks. J AOAC Int 2002;85;3;744-750

European Union Directive 95/45

Furukawa Suarez A et al. Impact of colour adjustment on flavour stability of pale lager beers with a range of distinct colouring agents. Food Chem 2011;125;850-859

Laws DRJ, Peppard TL. The stability of flavour constituents in alcoholic beverages. Food Chem 1982;9;131-146

Quesada Granados J et al. Influence of aging factors on the furanic aldehyde contents of matured brandies: aging markers. J Agric Food Chem 1996;44;1378-1381

Ratsimba V et al. Qualitative and quantitative evaluation of mono- and disaccharides in D-fructose, D-glucose and sucrose caramels by gas-liquid chromatography-mass spectrometry di-D-fructose dianhydrides as traces of caramel authenticity. J Chrom A 1999;844;283-293

Rodriguez Dodero MC et al. Phenolic compounds and furanic derivatives in the characterization and quality control of brandy de Jerez. J Agric Food Chem 2010;58;990;997

Scotch Whisky Regulations. Scotch Whisky Association 2009.

Sousa A et al. Isolation and structural characterization of antocyanin-furfuryl pigments. J Agric Food Chem 2010;58;5664-5669

Tsai PJ et al. Interactive role of color and antioxidant capacity in caramels. Food Res Int 2009;42;380-386

www.caramel.com (DD Williamson)

www.sethness-roquette.com

Cask sizes

noreply@blogger.com (Teemu Strengell) — Sat, 09 Apr 2011 16:42:00 +0000

Just a quick table about cask sizes.

Cask	Litres	Imperial gallons	US gallons
Bourbon barrel	159 (official barrel)		42	size varies 150-220l, commonly 180-200l
US beer barrel	117		31
UK barrel	164	36
Hogshead	250	54
UK ale barrel	146	32
Tun	955	210		"a ton"
Sherry shipping butt	491	108		30 arrobas,56 cases of 0.75l bottles or ½tun
Bota gorda, sherry cask	600			32arrobas
Sherry puncheon	667			40arrobas
Cognac	350			varies 270-450l
Cognac shipping cask	500-600
Bocoy	600-800			Spanish wine cask
Wine barrique	225			Bordeaux barrel
UK wine shipping barrel	119	26.25
Port pipe	528	116		varies 400-800l
Madeira cask	419-437	92-96
Marsala pipe	396	87
Marsala hogshead	200	44
Rum puncheon	410-455	90-100
Kilderkin	82	18		½ UK barrel
Firkin	41	9		Quarter of UK barrel
Bloodtub	34	7,5
Whisky quarter cask	125	27		½ hogshead
Whisky octave	46	10
Whisky puncheon	387-500	85-110		staves from 2 barrels

References:

Calabrese S. Cognac, liquid history. Cassell&Co 2001

González Gordon M. Sherry. Cassell Ltd 1972
Kilby, K. The cooper and his trade. John Baker Publishers Ltd 1971
Rainbird G. Sherry and the wines of Spain. 1966