It may seem as though the Roaster Project has come to a grinding halt. Fear not, it is alive and well. We have encountered the summer doldrums. I don’t know if it is true of other parts of the country, but in Arizona the summer is a very difficult  time to accomplish much. First of all, it is hot and it saps your strength and creative energy. The longer the heat continues, the more ennui sets in. Secondly, there is a focus on getting away from the heat. Vacationing takes hold and, while vacationing, one does not want to do serious mental lifting. Thirdly, others you may be relying upon have the same issues. Their reduced output and lack of availability only amplify the summer doldrums problem.

On the bright side, much creative design goes on “in the background” of the mind. I’ve had many interesting thoughts and am more encouraged than ever about the project. I will reveal more details in the next few weeks.

Our computer modeling subcontractor, Phoenix Analysis and Design Technologies, has been working diligently on how to model the bowl-shaped roasting vessel for the project. They have tried several different method and finally decided on one that seems to work well. This week, Jim Peters, our contact with PADT, invited us to the office to demonstrate the initial findings before signing a contract for the full modeling work.

PADT has many engineers on staff, of which some are off-site. In this case, Carlos, in their Philadelphia office did the initial work on refining the modeling of the bowl. We contacted Carlos by speakerphone and began discussing the models. In all cases, they used a perfect hemisphere for the bowl shape. Carlos came up with a model for an individual bean composed of several elements. He then began running the model with a few beans to test it. This takes just a couple of minutes for the computer to do the calculations and create a video of the results. Later, he tried 30,000 individual beans (about a half batch) to see how the bowl performed. The model is calculating the position of each bean, so the run time to make a single movie of the bowl in operation is approximately 1 day. When we model 60,000 beans (a full batch), the run time is about 1 week per video.

Reviewing the Results

Carlos lead us through the model results one by one while Jim Peters projected them on a screen for us to observe. Carlos also began to share some important observations  he had noticed while working with the model. First of all, the diverter cone in the bottom is very important to get the beans moving in the first place by getting them out of the central “dead spot”. I had intended for this to happen, as well as to divert the airflow from the heating jet into an appropriate pattern. Secondly, he noted that rotational speed of the bowl probably does not need to exceed 100 rpm but should be variable, which is easy to accomplish. Thirdly, the beans at any fixed rotational speed eventually “stall” or “stick” in a ring around the bowl. This is at the point when the rotational forces, gravity, and friction are all in balance. The faster the rotation, the higher up the “stall” ring occurs.

The Sticking Problem

Several videos were shown to demonstrate this phenomenon. Please click on this link to view a Bowl Model Video. Clearly, this is not a good thing. One of the design goals is excellent and consistent mixing of the beans. Having them stick in a ring means they are essentially fixed in place and not mixing at all (some burning, some raw). Carlos suggested that we consider a “scraper” to break up the ring and return it to the center of the bowl. He ran the model with a scraper to demonstrate the idea.

It seems to me that a better solution may be to make the bowl more shallow, perhaps on the order of a typical kitchen wok. This would speed up the beans and there would be no sticking. The key question is how does one force the beans to curl back over to the center of the bowl with out reaching some sort of equilibrium and stalling. This may include stationary vanes similar to the scrapers. As Carlos has demonstrated, scrapers can work and perhaps that is a good solution. The initial modeling has left quite a few questions to ponder.

The Next Step

So as not to waste money on endless modeling, I will need to narrow down the experiment to the most promising methods and have PADT model those. I would like to look at a number of variables, including bowl shape, bean return methods, speed, and batch size. Since the run time is highly dependent on the number of beans being tracked, I may suggest that we do quarter batch modeling until we find the best design, then ramp up the batch.

One of my goals is for the roaster to made as “locally” as possible. Why is that important? First of all, I want to support the local economy. Friends and customers of my other ventures live here and make their living closeby. They have faithfully supported my efforts over the years, so it is only right that I reciprocate when I have the opportunity. Secondly, there is the notion that not much is made in the US anymore — I would like to prove that wrong in my own way. Lastly, this is a very personal project for me — a work of industrial art. I want know each person who has a hand in making it a reality. I want to be able to talk face-to-face, visit their shop, watch my components being made, and truly appreciate their art and effort. That, gladly, forces it to be locally made.

Fortunately, building a roaster is not rocket science, but even if it were, the Town of Gilbert would still be a great place to build it! Not only are satellites built in Gilbert, many machine shops and fabricators that do aerospace quality work reside here. I believe that nearly all machining, metalworking, molding, welding, and finish work can be sourced in our town. A pleasurable task will be to search out and meet those talented individuals and companies.

Some specialized work may not be available in Gilbert, so I will then look in concentric rings radiating locally. For instance, I have been working with PADT in Tempe on computer aided modeling of the roasting vessel. I am quite certain that everything I will need can be obtained in the Valley. It is the home of numerous aerospace and high tech companies with staggeringly complex supply chains sourcing from smaller shops in the area.

What about “off the shelf” items such as motors, bearings, and the like? I will in all cases attempt to find ones made in Arizona and nearby states. After that, I will look for US made. This includes US made raw materials such as steel, aluminum, and wiring. Only if an item is not made in the US or the foreign part is clearly superior will I choose to use it.

It will be an interesting exercise to find out what can be made locally and what is made in the US. There will be further updates on my progress in sourcing. My numerical goals: 85% Arizona made and 95% US made by dollar value.

I always enjoy spending time in the company of fellow coffee enthusiasts. They are a committed and intense bunch, fueled into levity by consuming top quality caffeinated beverages. The discussion is unfailingly lively, centered around making the very best coffee. As a part of my home roasting experience, I decided to invite over my friend and earnest coffee disciple, Luis Till. The plan was to roast coffee a few different ways and evaluate the outcome. We were accompanied by our project photojournalist, Chanelle Richardson.

Luis is of Peruvian heritage and has a natural love for coffee. His brand is Amauta Coffee for which he has future plans. He is the ideal coffee man. For one thing, he is a continual learner, always trying learn from anyone who is willing to talk coffee. He also is open minded and not yet hardened into a dogmatic adherent to one coffee sect. Luis loves to roast and he has a very good cupping palate. We decided to meet up and roast one coffee (the Guatemalan Finca San Diego Buena Vista) on three different roasters to approximately the same degree of roast. The evening we met was probably one of the hottest in the Arizona summer: 106 °F and humid!

We started by roasting in the HotTop. Luis had never seen one in person, so before we started I gave him a tour of the features of the machine. He was impressed with the quality of the construction and the control system.

Since I wanted to be able to use the coffee in both an espresso machine and brewed, combined with the hard density of the bean, I decided to roast to a Viennese Roast. I used the normal roasting profile preset at the factory, but increased the final temperature (when the roasted coffee is ejected) to 424 °F up from the standard setting of 420°F. This results in the stopping the roast a few seconds into second crack. By the way, the indicated temperature on the HotTop is not the same as a true bean temperature. For more information on the correlation between indicated temperature and bean temperature, HotTop has a very useful graph. I was very pleased with the roast, as it spilled out into the cooling tray. The roasting time was about 17:00.

We then roasted with the hot air popcorn popper, which was the subject of “Home Roasting – Part 3″. Looking down the barrel we did our very best to try to match the roast color of the HotTop batch, which is very hard to do. It is a very fast roast, particularly with the starting air temperature of 106°F! The roasting time was 6:30 and the degree of roast was approximately the same.

It was Luis’ turn to roast. He brought his “old school” manual popcorn popper. Using the gas burner at our barbeque island, Luis preheated his popper. He has done many roasts using this popper and has developed an elaborate set of “rules of thumb” to ensure a quality roast. At just the right time, he added the green coffee and began vigorously shaking the popper back and forth. Watching the thermometer like a hawk, he would lift the pot on and off the heat as necessary to ramp the temperature.

Towards the end, Luis began cranking feverishly to keep the beans agitated and heated uniformly. It was harder to hear second crack, but we kept listening and watching the thermometer. At our best guess for similar degree of roast, Luis dumped the batch. The roast time was bout 14:00.

Luis uses “old school” cooling , as well. He deftly stirs the crackling hot beans in a colander with a wooden spoon. This helps separate chaff and fragments while cooling the beans.

Examining our work, we were rather pleased. We broke open a few beans to look at the cross section  and check the roast gradient.

In order (from left to right) are the HotTop roast, hot air popcorn popper, and manual popcorn popper. As can be seen from the photo, the HotTop and the manual popper had the best external uniformity. Also, both of the poppers were stopped a bit sooner and therefore are at a somewhat lower degree of roast. A reddish cast is evident in the manually popped beans, which would indicate the lightest roast of the three.

Cupping Notes

It is interesting to discern the differences created by both variation in degree of roast and  method of roasting. Since we used exactly the same coffee for each roast, that variable is constant. Luis and I each did cuppings at 24 and 48 hours for degassing. Luis used conventional cupping and v60. I used conventional cupping, Melitta pour over, black and with standardized amounts of half & half.

HotTop

Joe – Clearly the darkest of the roasts, bittersweet chocolate and dark cherry notes. Heaviest body, nice and syrupy. Through the E-61 Faema after 5 days made into espresso and cappuccino: chocolate covered cherry flavor and syrupy; muted by milk, but still pleasantly  evident.

Luis – Well developed beans with cocoa notes. Caramelization notes evident. Chocolate porter-like flavor and mouthfeel. Legs like fine wine indicate heavy body and held up well in milk.

Hot Air Popcorn Popper

Joe – Relatively bright, fresh berry note. Medium/light body, did not have nearly the soluable solids and did not stand up well to milk. Lacking complexity, seemed underdeveloped, which may be a result of fast roast times.

Luis – Some cocoa notes and possible smokiness. Light body and lacking in complexity. Noted that some of this may be due to inability to control the roast and hit exact degree of roast.

Manual Popcorn Popper

Joe – Chocolate and dark cherry notes with more forward fruit than the HotTop. Medium/heavy body. Steep roast gradient made it even lighter than the exterior would indicate. Good complexity. Steep roast gradient likely a result of the higher percentage of heat transfer via conduction.

Luis - Bright and juicy. Medium/light body and good complexity. Noted that it was sweeter than the other two.

We have tried the somewhat expensive but very flexible and controllable HotTop roaster. It is perhaps the ultimate home roaster and is able to produce coffee reliably at the same quality level as a good commercial drum roaster. What if all you have is a $20 bill in your pocket? Is home roasting a realistic option? The answer is “yes”. You’ll give up some control and ability to do profile roasting, but it is possible to achieve excellent results. The roaster for you is the humble hot air popcorn popper.

I chose the Cucina Bella available at Macy’s for $19.99. There are many others to choose from, but this particular model has some excellent features.

The best feature of this popper is the roasting chamber. It is the “swirl type” with slotted vents around the bottom of the chamber walls. This creates a swirling motion and helps blow chaff out of the roasting area. The other common style of popper has a central hole covered with screen, which I refer to as the “jet type”. It shoots a jet of hot air straight up through the green coffee beans and tumbles them. It is not quite as effective as the “swirl type” and, according to Sweet Maria’s, is much more likely to have a chaff fire. Another nice feature of the Bella Cucina is an ON/OFF switch, which is often absent in inexpensive poppers.

Before you begin roasting, it is important to gather the necessary tool. In addition to the popper, you will need a bowl to catch the chaff, a sheet pan for cooling the beans and a hot mitt or pot holder to remove the top of the popper. Set the chaff bowl under the spout of the popper.

You then measure out the correct amount of green coffee using the scoop provided. The popper uses the same volume of green coffee as popcorn kernels. This is about 1/3 of a cup or 75gr. Using the correct volume of beans is critical to obtaining a good roast. The fluidized bed is a balance of airflow and mass. Since the airflow of the Bella Cucina is fixed, the mass of the beans must be carefully standardized, as well. This sounds like a small amount of coffee (you will end up with about 60gr), but it is sufficient for a good pot of coffee or about 8 shots of espresso.

Dump the green coffee into the roasting chamber and put the clear grey air chute on top. It will direct the hot air into the chaff collecting bowl.

Turn the popper on. Immediately the beans will begin to swirl. This roaster is much faster than HotTop or a commercial shop-scale drum roaster. The roast time is 6 to 7 minutes versus up to 18 minutes, so you need to watch carefully. All of the sights, smells, and sounds we discussed in the previous post on the HotTop occur here, just much more quickly. Soon the beans are yellow, then cinnamon with the attending aromas.

Around first crack, the chaff blows off of the coffee and collects in the bowl. This occurs 3 to 4 minutes into the roasting process. After a period of the beans continuing to darken, second crack begins and the roasting process accelerates madly. Be prepared to end the roast and “cool” the beans!

Turn off the popper, take the top off  and dump the coffee onto the sheet pan. This is obviously a very crude way of ending a roast and cooling the coffee, but it works!

After a couple of minutes of shaking the roasted beans on the sheet pan, they are cool to the touch. As you can see, the popper did a good job of bean development and the consistency between beans is not bad. Once cooled, let the beans rest for a day before making brewed coffee and two or three days for espresso.

The next day, I tasted the Guatemala Finca San Diego Buena Vista that had been roasted in the popcorn popper. The cup quality was quite good. It was a bit brighter than the same coffee roasted in the HotTop and perhaps a bit less complex. Chanelle Richardson (the project photojournalist) also tasted it and thought it wonderful, as well.

So there it is! You can do a good job of home roasting with an investment of $20. Why not give it a try? In my final post on home roasting, next week, we will be doing a Roast Fest using four different home roasters with the help of a guest roastmaster.

I’ve started doing small batch home roasting with  a new HotTop coffee roaster. It is a pretty advanced drum roaster that operates similarly to a shop drum roaster. The roasting vessel is a small perforated drum with a capacity of 250gr (about 8oz) of green coffee. Heat is provided by an electric element and there is a variable speed fan used to control airflow through the roaster. Roasted coffee is cooled in a separate cooling tray that stirs the coffee and has a separate cooling fan. The whole process is run by a control system run by a micro-controller which has easy to use controls and a great display for monitoring the progress. The HotTop is solidly built in and is extremely well designed.

The perforated roasting drum is made of stainless steel and has a welded wire agitator to move the beans front to back within the drum. The loading of the drum takes place at the rear. Beans are dropped into the cooling tray from the back, as well, via a solenoid operated ejection door. Temperature measurements are taken at the back of the drum, while the front of the drum has a large glass window to watch the beans roasting.

Starting the Roasting Process

The first thing I did was read the instructions. As a guy, it is against my nature to read instructions, but a coffee roaster has a reasonable chance of catching fire if improperly operated and maintained. Lawyers had definitely been involved in the verbiage as “no brainers” such as “do not submerge the roaster in water” were included with more likely operator issues. The documentation is well written and the HotTop website yields even more helpful and advanced material (including step-by-step guides on replacing parts and doing repairs).

The most important item to have, other than the roaster, is some top quality green coffee. I purchased five pounds of Guatemalan Finca San Diego Buena Vista (St. James Beautiful View Farm) from SweetMaria’s. It seemed to be a good choice in that it could make both an excellent coffee for drip and yet be roasted slightly darker for a single origin espresso. Inspecting the beans, I found them to be of uniform size and free of defects: a clean preparation.

The roaster is designed to use a fixed batch size of 250gr. The instructions state that you can vary the batch size slightly to affect the roasting rate. I decided to go with the standard batch and weighed out the exact amount.

After powering the roaster up, you can select to run it manually or to run a profile automatically. A profile is essentially a program of data points for that set the roasting path. These may include time, temperature, fan speed, heater output, etc. The HotTop comes with a standard profile that can be modified as you roast or you can roast manually (adjusting the variables over time). If you roast manually, the roaster can save your profile for repeating in the future. This is handy if you want to standardize a roast of a particular coffee. The roaster can save up to three custom profiles in addition to the standard one.

I selected the standard profile, which has an ending time of  18:00 minutes at a final temperature of 420F (whichever comes first). The profile changes the fan speed and heating element power level over time during the various phases of roasting.

In all cases, the starting point for a roast is 167F. The roaster either heats up or cools down (after a roast) to hit this temperature. Since the profiles are based upon a known starting point, this is very important. The display shows “P H” until the starting temperature is achieved then beeps to indicate loading time.

At the loading beep, you remove the upper door and insert a black plastic funnel. Pour the green beans into the funnel, down the chute and replace the door when you are finished. The roasting process has begun.

Monitoring and Adjusting the Roasting Process

The roasting process starts out quietly with the tumbling of the beans in the drum being all you hear. Observing the roasting process to make adjustments is accomplished in four ways. First, the beans can be seen though the window at the front of the roaster (color changes,chaff, etc.). Second, the temperature, time and system variables can bee seen on the display. Third, we listen for certain tell-tale sounds (first crack, second crack, audible alerts). Lastly, we can smell the changes occurring as the beans roast.

Early in the roasting process, not much appears to happen. The beans are starting to dry out as the moisture escapes and the color turns from jadite green to straw colored. The aroma changes from grass/alfalfa to bread baking.
The control panel and display show the minutes remaining for roast completion and the current temperature. It also shows the fan speed  (in this case OFF) and the heating element power (in this case 100%). At any time you can adjust any of these variables to deviate from the standard profile. I did change the ending temperature to 424F because I am roasting this batch for single origin espresso.

The first audible stage is called “first crack”. It starts out with a few singular sharp popping sounds and then builds to a crescendo and trails off later. During this phase certain chemical reactions take place and the chaff (or silver skin) detaches from the bean as the bean expands in size. The chaff is removed from the drum by applying air and collecting it in a tray below. At this point the aroma smells like coffee and smoke rises from the vents of the machine.

Ending the Roast and Cooling

The roasting process accelerates from this point on and vigilance is required. The color of the bean changes rapidly from cinnamon to milk chocolate brown and the beans continue to expand. Soon a second audible stage begins called “second crack”. Similar to first crack, but more subtle, the coffee undergoes major changes in flavor and color. The aroma becomes more bittersweet and the amount of smoke increases as the color of the beans go towards bittersweet chocolate. If you continue further, the smoke becomes more pungent, the beans become darker and the oils come to the surface. You cannot roast them dark enough to become completely black (which is ruining the beans anyhow) because the HotTop has a preset cutoff at 428F which can not be adjusted.

At 424F, the profile ended and the roaster automatically ejected the beans. At this point the drum continues turning to drive all of the bean out of the drum, out the ejection chute and into the cooling tray.

The cooling tray runs for 5 minutes. The stirring blades are driven by a motor that moves the beans both clockwise and then counterclockwise. A separate fan draws cooling air through the beans.

After the beans have cooled, you reweigh the coffee to calculate weight loss during roasting. In this case, the ending weight was 204gr and the charge weight was 250gr, which is a weight loss of 46gr or 18%. This would be classified as “Vienese Roast”. The range in which most roasting is done is a 15% to 19% weight loss and that corresponds to stopping the roasting process just before second crack through nearing the end of second crack and degree of roast “City Roast” though “French Roast”.

At this point, the roaster can either be turned off or start another batch. If starting another batch, the roaster will cool itself to 167F before allowing the roasting process to begin.

The Final Result

The photo above show the green coffee and the roasted coffee. The expansion of the beans is obvious. Also note the silver skin on some of the green coffee prior to roasting and the tiny amount left in the groove of the roasted coffee. At this point, the coffee should be allowed to rest an de-gas for a while (varies from 1 day to 3 days depending on how the coffee will be used). De-gassing is the natural release of carbon dioxide gas that builds up inside the cells during the roasting process. Once rested, enjoy the coffee!

Some Conclusions

The HotTop is a great little drum roaster. It is well made and easy to use. The control system allows profile roasting and manual control which enables one to roast coffee with a similar level of control that a commercial shop roaster offers. The separate cooling tray is a necessary feature that most home roasters do not have. Parts and technical support are readily available. If you don’t mind spending the money (about $700), it is an excellent investment. If $20 is more your budget, in my next post we will roast with a hot air popcorn popper!

Despite what you may have heard from people in the coffee industry, it is easy to roast coffee at home. The process of roasting coffee is actually quite simple. The basic idea is to take raw, green coffee beans and heat them uniformly with the correct amount of heat input to drive off the moisture and make some chemical reactions occur that also happen to make the color of the bean progressively “browner”. In the earlier days, it was commonly done in a pan over a flame. This tended to scorch the beans, but there are some simple methods that do a respectable job.

Why Roast at Home?

If the idea of roasting your own coffee holds no interest to you, you should continue to buy beans from a respectable roaster. If it does interest you, then there are many good reasons to roast at home. First, just for the fun of it. The process of roasting coffee is enjoyable AND it is a skill that produces a product that can enjoy daily and share with friends. It is much easier than brewing beer and takes much less time. Second, it is allows you to tailor coffee to your exact liking. You will learn which green coffees are your favorites and then roast them in a way that the develops a flavor profile that you like. Third, you control the freshness of your coffee. By roasting in tiny batches, you can ensure that the coffee you drink is at the peak of flavor development on the freshness curve (for instance, you want to wait a few days after roasting for espresso). Lastly, you can save some money. Even though you will pay more for the green coffee than a commercial roaster does (due to repackaging into smaller increments), you will end up with roasted coffee that costs less. The savings varies, but is probably in the 50% range.

Home Roasted vs. Commercially Roasted Coffee

Can home roasted coffee compare with craft roasted coffee from a great commercial roaster? The answer is a qualified “yes” … yes if (1) you are skilled at roasting, (2) you buy fine green coffee, and (3) you have the proper equipment.

When you roast your first few batches, you will be amazed at how simple coffee roasting really is. After roasting a couple of dozen batches, you will realize that you actually know very little about roasting coffee. Assuming you continue and keep working at the craft and have done hundreds of roasts, you will finally understand the roasting process variables quite well. As the great chef, Thomas Keller, says: “you don’t know how to make a croissant until you’ve made 10,000 of them”. Does that mean you shouldn’t start, because it is daunting? The challenge of honing a craft and going through the process of misplaced confidence, disillusionment, and final mastery is good for the soul. There are no shortcuts.

Finding excellent green coffee is a matter of finding a trusted supplier. Good sources include your favorite local roaster, as well as on-line vendors. If buying on-line, look at blogs to see what others say about the quality of the green coffees a purveyor offers.

In the next section, I discuss equipment. Assuming that you have equipment that is capable of roasting properly and has the controls needed for a roastmaster to manipulate variables, you use excellent green coffee, AND you are in the mastery phase of roasting skill, there is no reason that you cannot produce outstanding coffee at home.

What Sort of Equipment is Needed?

I started roasting coffee as a hobbyist in 1987. That hobby lead to a chain of coffeehouses called “The Coffee Plantation” which is the subject of several archived posts on this blog. At that time, the equipment options were very limited. I used a hot air popcorn popper.

A hot air popcorn popper is actually a very cleverly designed (and cheap) fluidized bed roaster. If you use an unmodified one, you have zero controls except an on/off switch and the weight of coffee that you put into the chamber. The weight of coffee you put into the popper is critical to proper roasting. You have to watch the coffee as it starts to tumble in the air when you turn the popper on. If the coffee shoots up, you don’t have enough. If it just kind of sits there and jumps up in “puffs”, it is too heavy. When the beans are uniformly swirling and tumbling, you have found the magic weight for a perfect fluidized bed. Dump the beans out and weigh them. This is the charge weight you will use for future roasts. Start the roaster up and watch the roasting process. Chaff will blow off and out of the roaster and smoke will appear. I suggest roasting outdoors for this reason. In my next post, I will discuss in more detail the roasting process. Suffice it to say that the hot air popcorn popper is your best value in a starting roaster. Some of the better designs can be found on eBay for $30 or less.

There are now on the market many a glorified hot air popcorn popper that include the ability to manipulate more variables. Some have chaff filters, others have cooling cycles, but they all work on the same principle. By the way, there are many commercial fluidized bed roasters, so these popcorn popper variants are in good company. The main difference is that the poppers are basic and electric and the commercial roasters are generally gas fired and have advanced control systems. New hot air roasters for home cost $100 to $200.

Also on the market are home versions of drum roasters. They all use electric heating elements and have some measure of control for airflow and heat. Some have advanced displays and control systems. Most do cooling within the roasting drum, but at least one has a separate cooling tray. Since drum roasters are the industry standard for commercially roasted specialty coffee, a home drum roaster is more likely to produce coffee of a similar quality. The additional controls also enable the home roastmaster to be able to control the roast at a much finer level. Home drum roasters cost $300 to $1,000.

If you have plenty of cash to spare and cost is no object, you can purchase a small roaster (1 lb – 2 lb capacity) made by a commercial roaster manufacturer. These are miniature versions of commercial drum roasters. Plan on shelling out $5,000 for a new one.

What I Bought

I’ve been wanting to roast again to start honing my skill at the craft. Eventually, I will want to build a sample roaster built on the same principle as my larger scale commercial roaster. Not content to wait, I started looking for a roaster that would suit my needs. I went to the best known website for home roasters, Sweet Maria’s, and looked at the various roasters they sell.

I knew that I wanted a drum style so that there would be some element of conduction as a part of the roasting process. I also wanted to have relatively advanced controls and a separate cooling tray. The best choice for my needs seemed to be the HotTop Roaster Basic Model. The reviews indicated that it is robust and can produce some excellent roasts. The roaster has arrived at my home and I will be analyzing it and demonstrating its use in my next post.

Since I have a bit of time on my hands (while working on computer modeling of the roasting vessel), I wanted to take the opportunity to write about some general coffee topics.

Espresso bars are a part of my daily ritual. Starting the morning with a cappuccino and later moving on to a macchiatto or espresso, properly crafted, brightens my day. It is not just the product that stimulates, but the experience, as well. Espresso bars have a long tradition originating in Italy. Virtually all of the basic equipment, techniques, and beverages were developed there. Even today, the majority of espresso bar equipment is of Italian design and manufacture. Espresso bars are an integral part of Italian life.

Since the 1980′s, “espresso” bars have become commonplace in the US. Starbucks now dominates the US market. However, there is a flourishing group of independent espresso bars which are capturing market share. This has added a richness to the coffee scene. I make it a point to visit espresso bars in our area and whenever we travel. I’m also a partner in an espresso bar (the E61 Bar) at Liberty Market (Gilbert, AZ). Due to convenience and preference, the majority of the espresso drinks I consume are made at Liberty Market or by me at the espresso bar in my home (we have a full commercial espresso bar in our front room to serve guests).

With the resurgence of “espresso” bars one finds a huge range from exquisite to tragic. Exquisite experiences are rare and tragic are far too common.  Are there some signs alerting the customer as to what sort of experience they should expect? I use a few key observations to help me decide whether I should just turn around and walk out before ordering. By the way, you may note my use of “espresso” bar. I use it for two reasons: (1) in the US we use much more milk than in a true Italian espresso bar and (2) most US operations are also coffee bars serving brewed coffee, again not a part of the Italian tradition. Some will say that I am too rigid by using great Italian espresso bars as a measuring stick, but I would also use great Japanese sushi bars as a measuring stick for sushi, not new American sushi houses that focus on rolls.

The Golden Equation

My assessment of an espresso bar is done in precisely the same way I evaluate any other food or beverage operation. I use a yardstick which I refer to as the Golden Equation. All of the places I love fit the equation. It doesn’t mean that they are successful or will last — just that it is the kind of place that I would seek out.

Passion + Craft + Quality Ingredients = An Outstanding Product

Let’s break down the espresso bar experience into the three components and what to look for as indicators.

Passion

Coffee is a product that stirs the passions. It is a stimulant. It comes from far away places. It involves elaborate preparation to make the final product. If you go to an espresso bar and the “barista” is bored and lifeless — it is time to leave. Passionless people make passionless products. Bored people make boring products. If the “barista” is mainly interested in chatting mindlessly with his or her fellow “barista” — it is time to leave. Mindless people make mindless drinks and careless mistakes. On the other hand, if the barista is engaging perhaps even over-proud, this is a good sign.

Craft

The proper making of an espresso drink is at once simple and infinitely complex. The great barista makes it all look so simple and quick. They have spent years honing their craft — all of the tiny details required to consistently deliver an exquisite experience. The traditional drinks and techniques have been developed over decades to produce perfection. One can observe several signs that the craft is honored at an espresso bar. Is the bar clean or covered with grinds, grossness, and filth? Craftsmen do not keep a dirty workspace. Is the equipment in perfect shape and polished? Craftsman are proud of the tools of their trade. Are there real ceramic cups on top of the espresso machine? Craftsman always prefer to use traditional ceramic drinkware because they know the experience is so much better. If the default drinkware is paper — time to leave. Are there espresso grinders grinding and hand tamping going on? If the espresso machine is doing all of this, it has replaced the craftsman — time to leave. Can the “barista” push a button and not have to watch the espresso shots building? If so, this is button-pushing, not craft. A true barista must watch the shots because the machine is not automatic and he or she “reads” each shot by observing the flow, color changes, and development of crema. When the barista steams milk, is it a noisy affair similar to a jet taking off? If so, there is a problem with technique. Develop an ear for what great steaming sounds like.

Quality Ingredients

Espresso drinks are made with very few ingredients. Espresso, itself is made with one — coffee. The coffee that is used must be of high quality and properly roasted for espresso. It must also be fresh. If the espresso bar has grinders filled to the top with coffee and the doser is full of ground coffee, this promotes staling of the coffee. The barista should be able to tell you who roasted the coffee and what sort of coffee it is. Furthermore, the bar should have a system of rotation to ensure that the coffee turns over frequently. Other perishable ingredients, such as milk should be fresh and ordered frequently. Syrups, if used should taste pure and true on their own, not fake and sickeningly sweet. If the barista re-steams a pitcher of milk — it is time to leave. Milk cannot be re-steamed and have correct flavor.

A List of Extra Points

If an espresso bar meets the basic criteria, they can also earn some extra points.

1. Considers the needs of pure espresso drinkers – most places go for a dark roast that is unbalanced for pure espresso (great for lattes) and do not have proper drinkware.

2. Roasts their own coffee – passionate craftsmen want to go as deep in the process as they can to control quality and freshness.

3. Eager to educate – passionate craftsmen want to increase the enjoyment of others by sharing knowledge and through product tasting.

4. Properly sized and constructed drinkware – quality Italian-made heavy ceramic drinkware is the gold standard for a reason: heat retention, beauty, and an optimal experience.

5. Some restrictions held dear (but consistent)- passionate baristas may not offer syrups, low fat or skim milk, artificial sweeteners and the like, if they believe them bad for the craft.

6. They are fast – a properly made drink tastes best when made at the proper pace. Slow baristas do not make better drinks — the drinks deteriorate over time, not improve.

7. Latte art – if the latte art does not adversely affect drink quality, it is an added touch of craftsmanship.

8. Bar seating and stand-up bars – adds to the experience and is very traditional.

A List of Demerits

There are many smaller details that detract from a proper espresso bar experience. I’ve listed a few of the more common signs that a place is not on the top of its game.

1. There is a giant menu board – when was the last time your went to a good bar or restaurant that had a prominent menu  board?

2. The menu board has slide in-letters or vinyl letters – additional demerits for corporate fast food feel, which is the opposite of passion for the craft.

3. Oversized drinks – traditional drinks are not huge, they are small and balanced.

4. Use terms like “Tall”, “Grande”, “Venti” and the like – craftsmen abhor the idea of confusing and supersizing the customer with milk and sugar.

5. Promotion of strange jargon (e.g. skinny, two pump, sugar free vanilla…) – craftsmen promote traditional terms of quality such as ristretto, lungo, etc.

6. Not grinding to order – this may work in a high volume bar in Italy, but in the US it is important to grind espresso to order for freshness.

7. Using the plastic tamper on the doser – it is impossible to use this effectively … most good places remove them entirely.

8. Espresso with straw colored crema that dissipates rapidly leaving a hole – barista is not paying attention to grind and shot timing.

9. Drinks in the wrong sized drinkware – cappuccino cups are about 5oz. They should be filled to the top. A double espresso does not belong in a cappuccino cup.

10. Milk foam with coarse texture and visible bubbles – the barista did not steam the milk properly and let it pass, not a good sign of the craft.

11. Chipped or cracked drinkware – dishonors the craft by showing carelessness and lack of interest in the customer’s experience.

12. No demi-tasse spoons – shows complete lack of understanding for lovers of espresso, macchiatto, and cappuccino.

13. Use of a blender – LOUD! Did I say LOUD? Disruptive of the espresso bar experience and more appropriate at a soda fountain.

I’ve been wanting to sketch the form of the roaster for some time now. It is said that “form follows function”. I believe that to some degree, however many of my favorite industrial designs break the rule or at least go a bit further.

For instance, one of my favorite designs of all times is the Vespa scooter. The form does start by following function. The basic idea is to create two-wheeled transportation that is economical, simple to operate and that a lady wearing a dress can ride. This leads to a step-though design (unlike a motorcycle) and a leg shield, both of which are iconic Vespa features. The body encloses the mechanicals, so that clothes cannot get soiled. The controls are simple bicycle-like affairs that make learning to ride very easy. However, the designers went to the additional step of infusing a measure of beauty into the scooter. They added flowing lines, grace in the curve of the headlight enclosure, and many smaller details that make it a work of art. While there are other “functional” scooters from the same era, none are as beloved and timeless as the Vespa.

I take a similar approach to design. Function is very important: beauty, pattern and presence are also very important. Here’s how I came up with the drawing shown below, which is a possible form of the roaster.

First, I consider function. A roaster needs (1) a place for the green, unroasted coffee to be held, (2) a roasting chamber, (3) a cooling chamber, and (4) areas where burners, blowers, ductwork and motors needed to operate are housed. Since I am currently focused on using a bowl as the roasting vessel, it makes sense for me to house the bowl in a round form. The form could be spherical our cylindrical: I chose spherical due to my fascination with the Automium. Furthermore, the green coffee hold may include preheating of the beans to drive off moisture and set a uniform starting condition for the roasting vessel. This means that it has a similar function to the roasting vessel: heating and mixing the beans. The cooling chamber is essentially the inverse of the roasting chamber: removing heat and mixing the beans. Since all three functions are closely related, it makes it possible for the form of each  be similar, hence the three spheres.

This plays nicely into two design features I enjoy: pattern and odd numbers. The repeating spheres and the number being three looks good to my eye. I have added the connecting chutes for the beans and the necessary ductwork for the roasting vessel (this still needs refinement). The bases for the roasting sphere and the cooling sphere contain the drive motors to run bowls or mixing arms (the cooler?) for each. The various blowers, burners, gas controls, and ductwork are in a housing behind the spheres. Each sphere has a window so that one may observe the activity going on inside the sphere.

The design is simply an initial idea. I will be refining the basic idea and adding more detail. On the other hand, I may just toss this design out, if a better one comes to mind.

As stated in previous posts, I believe that computer modeling of the roasting vessel is a critical step in developing a workable design. By using a computer model, I will be able to dial in the likely dimensions and shape of the bowl. I ‘ll also be able to visualize the flow of the beans within the vessel to have a better understanding of the dynamics of the process.

A commentator on this blog (Jeff Strain) suggested that I check out his firm, Phoenix Analysis & Design Technologies (PADT). They do computer modeling for all sorts of mechanical systems and fluid flow. Jeff showed me a simple version of what they could do on his laptop. I was intrigued enough with the power and flexibility of the model to schedule a visit to their offices in south Tempe. Our photojournalist, Chanelle Richardson also went on the trip.

We met with Jim Peters and Clinton Smith, who are engineers in the division that does computer modeling. As an introduction, I described the roasting process and some of the important parameters. We then discussed drum roasters and finally the basics of my design (a bowl roaster). Jim and Clinton explained some of the ways they could model the roasting vessel. We jointly decided that modeling 66,000 individual beans (approximately the maximum capacity of the roaster) flowing around within the bowl was both reasonable and likely to give the best results. They showed us how the modeling results might  be visualized and gave lots of encouragement.

PADT also does “Rapid Manufacturing”, which mean that they have the capability of converting a CAD  drawing (essential a part drafted on the computer, rather than on paper) into a finished part using various 3-D printers. Jim and Clinton took us on a tour to see how this is done. They use several different methods depending on what the final part looks like. Most rely upon lasers to “draw” the part, layer-by-layer into either a resin, which hardens, or a powdered material which melts and then hardens. Another method uses tiny blobs of molten plastic deposited in layers. The results are nothing short of phenomenal. The plastic parts can then be used directly or as the form for creating a mold.

We were shown samples of what can be done. Lots of medical devices such as individualized hip replacement components were made in titanium from the plastic parts. To demonstrate their capabilities, they also made such playthings as Rubrik’s Cubes all done in one shot with full movement of all of the pieces. It was very impressive. Rapid manufacturing is something ideally suited for a project like the Roaster Project where only one machine is being made. I could envision prototype parts being made for evaluation and mold for casting metal support structures. All-in-all it was a very enlightening and encouraging field trip.