Recalling our interview in December of last year, right before the virus hitting, we talked to Ed, a PhD candidate and beer scientist, on his research potential impact of using proteomics approach for better development of brewing process. We would like to congratulate him on the licensing deal of the wild yeast variety discovered during his research to the local brewery at Newstead Brewing Co for further scaling and production for widespread consumption.

Many crucial elements go into the selection process for a yeast to be usable and the subsequence well-received by the consumer. First is that they have to be a naturally occurring yeast species due allege public widespread of distrust in a lab-created organism through genetic modification technology (Callaway, 2016; Tenbült et al., 2008). However, genetic screening of organism has been using in industry to shortlist and identify novel strange for the development of new beverages (Callaway, 2016). In particular to mainstream industrial brewing ale, some of the desirable properties found in are limited or low sporulation, high maltotriose metabolism, low production of off flavour aromatic compounds (Gallone et al., 2016; Gonçalves et al., 2016).

For an alternative beer brewing yeast to be successful, it is necessary to have respectable growth rates in highly scaleable brewing conditions. These requirements are can be high or low temperature depending on the type of beer (Rudin & Hough, 1959). Due to the environment within the industrial growing vat contains a very large amount of liquid, to be scale able, the organism also needs to grow well in under high pressure (B. R. Gibson et al., 2007).

With growing well and being able to convert the large amount of carbohydrates in the mash into alcohol being the essential properties, commercially viable alternative brewing yeast also provides unique flavour profiles and texture (B. Gibson et al., 2017). Here, after the laborious process of searching, cultivating and testing of the wide varieties of wild yeast across the University of Queensland St Lucia campus, Ed has been able to select a species suitable for further development into industrial scale.

The favoured yeast was selected for its white peach, lychee and fresh-baked sourdough flavours and was one of more than 150 varieties painstakingly gathered from trees, leaves and flowers at UQ’s St Lucia campus.

UQ News press release

References

Callaway, E. (2016). Tapping genetics for better beer. Nature News, 535(7613), 484.

Gallone, B., Steensels, J., Prahl, T., Soriaga, L., Saels, V., Herrera-Malaver, B., Merlevede, A., Roncoroni, M., Voordeckers, K., Miraglia, L., & others. (2016). Domestication and divergence of Saccharomyces cerevisiae beer yeasts. Cell, 166(6), 1397–1410.

Gibson, B., Geertman, J., Hittinger, C., Krogerus, K., Libkind, D., Louis, E., Magalhães, F., & Sampaio, J. (2017). New yeasts—New brews: Modern approaches to brewing yeast design and development. FEMS Yeast Research, 17(4).

Gibson, B. R., Lawrence, S. J., Leclaire, J. P., Powell, C. D., & Smart, K. A. (2007). Yeast responses to stresses associated with industrial brewery handling. FEMS Microbiology Reviews, 31(5), 535–569.

Gonçalves, M., Pontes, A., Almeida, P., Barbosa, R., Serra, M., Libkind, D., Hutzler, M., Gonçalves, P., & Sampaio, J. P. (2016). Distinct domestication trajectories in top-fermenting beer yeasts and wine yeasts. Current Biology, 26(20), 2750–2761.

Rudin, A., & Hough, J. (1959). Influence of yeast strain on production of beer by continuous fermentation. Journal of the Institute of Brewing, 65(5), 410–414.

Tenbült, P., De Vries, N. K., van Breukelen, G., Dreezens, E., & Martijn, C. (2008). Acceptance of genetically modified foods: The relation between technology and evaluation. Appetite, 51(1), 129–136.

Down on memory lane

... One night, while scrolling on FB - since I belong to a cooking group - I stumbled across this "Dalgona coffee post" and being a coffee lover (Guatemala is not only coffee of course, but sure produces the best in the world, not afraid to say this at all...). I decided to take a look at it and learn why this was trending, and lo and behold the coffee my mom would put us - me and my two sisters - beat, for I do not know how long, was there and it had a name not just beaten coffee - like she used to call it - ... and the memories from my childhood came pouring back...

Growing up back home, in Guatemala, we used to spend most of our weekend afternoons - if we were not out with Dad camping or "exploring" as he would call it - in our paternal grandparents house. Every Sunday afternoon after sharing lunch together; which later on became almost a matter of trying to fight against time, after Grandma died and the gatherings changed to spending Saturdays and Sundays together over lunch.

While beating the coffee with our spoons, we would sit around the table and hear Mom and Dad talk with our Grandparents - later on, my Aunt joined the lunches after Grandma died, alongside with our cousin -, about politics, family history and stories. I used to love those lunches, it would be a time in which we would all be together and chat, laugh as well as eat good food. This coffee, at the time unimportant, is now part of my cherished memories. Therefore, now I would like to share how we did it, with the change that instead of doing it by hand - like we did back then -, we used a hand mixer and instead of just pouring hot water to it, we scooped the foam over milk with ice cubes.

Beaten coffee my way (Dalgona coffee as I have come to learn now):

1 serving

2 tablespoons of instant coffee of your choice (I prefer Nescafe, is a little less bitter than Lavazza - I normally do not use instant coffee)

2 tablespoons of sugar (or less if you wish to)

2 tablespoon of water

Cold milk with ice cubes (tall, short glass or mug... your choice)

In a bowl, mix all the ingredients.

Beat until the foam changes to a light almost beige color.

Scoop over cold milk and enjoy.

Thanks Toan, for the pics.

Monosodium glutamate, otherwise known as MSG, is a sodium salt of the naturally occurring amino acid, L-glutamic acid (the primary form in commercial manufacture) or glutamate (anion form of glutamic acid) (PubChem, n.d.). One of the most abundant non-essential amino acids, key component in protein chains of every living organism, as well as a vital component in neuro messaging. in this post we review its discovery and how now is making a comeback to modern cooking by the hand of famous chefs.

Outside of its role in the human body as an amino acid. Glutamate has been part of other culture’s diet for thousands of years. In fact, glutamate was not initially discovered as a primary amino acid. 

Its history as a kitchen flavor started in 1866, when the german chemist Karl Heinrich Ritthausen was studying the proteome [mfn]the protein content of cells, tissues, and organisms[/mfn] of wheat gluten within a solution of alcohol and water (Vickery & Schmidt, 1931). Glutamic acid crystal was discovered by treating wheat with sulfuric acid (Vickery & Schmidt, 1931; Yamaguchi & Ninomiya, 1998). It was a hydrolysis reaction between gluten, a protein in wheat, and the acid, resulted in glutamate salt as we know it (Vickery & Schmidt, 1931; Yamaguchi & Ninomiya, 1998). However, he did not explore the salt crystals any further and only mentioned that it had a faint acidic taste (Yamaguchi & Ninomiya, 1998). After that, MSG returned again to the shadows. 

In nature, glutamate is widely available as one of the primary amino acids in cellular biochemistry. This amino acid is a crucial player in the nitrogen metabolism pathway where excess nitrogen would be converted into ammonia; that the human body would then discard in urine. (Hubbard & Binder, 2016)

MSG through history: From dashi [mfn]basic soup stock used in Japanese cooking[/mfn] to MSG

Although being discovered in 1866, glutamate was not yet known for its current flavor enhancing profile, despite the fact that ingredients with high glutamate content have been used for a long time.  

As part of cooking, it can be often found in large amounts, in fermented foods (Otsuka, 1998; Tamang et al., 2010; Yamaguchi & Ninomiya, 1998; Yoshida, 1998). Traditionally, among fermented foods, fish sauce and paste, contain a high amount of free glutamate. Their usage has been shown to be spanning around the globe from the Ancient Roman and Greek to the first official record of usage in Asian cuisine in the 2^nd century B.C. (Yoshida, 1998). It has been speculated that the taste enhancer effect of fish sauce was discovered from an accidentally fermented salted fish mixture where it was found to be an acceptable complementary condiment to the traditional food (Tamang et al., 2010).

Pre-commercial production

In spite of having such a long history in many civilizations cuisine, the taste profile of glutamate was only defined by Professor Kikunae Ikeda at the Imperial University of Tokyo in 1907 (Yamaguchi & Ninomiya, 1998). The compound was isolated as the major tasting component of kombu broth or dashi, a stock made from boiling dried kelp (Osawa, 2012). It was noticed that the compound contributed with a distinctly different taste other than that of the currently defined basic tastes (sweet, salty, sour and bitter) (Yamaguchi & Ninomiya, 1998) . Ikeda gave the taste profile the name “Umami” (Yamaguchi & Ninomiya, 1998). The word according to the Oxford dictionary literally means deliciousness in Japanese.

Since glutamate is not just a compound found in kelp, a student of Ikeda later also identified glutamate providing the same taste profile in dried skipjack [mfn]a species of tuna fish[/mfn] together with other compounds with umami tasting characteristics (Yamaguchi & Ninomiya, 1998). So far, we have discovered several compounds like L-aspartic acid and succinic acid, tartaric acid and lactic acid with similar taste profile as that of glutamate (Suess et al., 2015). The effectiveness of MSG flavor can be improved even more when used in presence of compound like guanosine or inosine 5′-monophosphate (Suess et al., 2015).

The umami taste profile: How do humans taste the umami flavor

Umami, the taste of dashi that Ikeda noted for glutamate, is the flavor enhancing effect created by the compound. It has been noted that while the current flow of ions and changing of ion channel conductance create the neurological response to salty and sour flavor, umami, sweet and bitter interact through activation of G-protein coupled receptors (Lindemann, 2000). A study published in 2000 showed that, for umami flavor specifically, glutamate interacts with the nervous system through a truncated version of the mGluR4 glutamate receptor (Lindemann, 2000). mGluR4 exists in the brain and is responsible for modulating the expression of the neuro messenger cAMP (Lindemann, 2000). The study suggested that umami can be the result of a combination of a large number of cellular sustained hyperpolarization and a small amount of transient depolarization responses of taste bud cells (Lindemann, 2000).

DID YOU KNOW:

A loanword from the Japanese(うま味), umami can be translated as "pleasant savory taste." This neologism was coined in 1908 by Japanese chemist Kikunae Ikeda from a nominalization of umai (うまい) "delicious." The compound 旨味 (with mi (味) "taste") is used for a more general sense of a food as delicious.

Ikeda suggested that the origin of how human had evolved this ability for detection of glutamate, and  to differentiate the umami flavor from other flavor profiles is directly related to the ability of humans to identify readily accessible and protein rich food (Mouritsen & Styrbæk, 2014). Due to the large energy requirement for supporting a large brain, this particular ability also likely to contribute to the human evolution toward expanding our brain size (Williams & Hill, 2017). Despite its taste being much more subtle than salt, he also noted that our palate sensitivity to glutamate is ten times greater than that of salt (Mouritsen & Styrbæk, 2014). In usage, Ikeda also observed that glutamate can amplify our sensitivity to salt (Mouritsen & Styrbæk, 2014). This has also made glutamate extremely attractive to the processed food industry as a food additive (Maluly et al., 2017). Making possible to perceive food to be  saltier than it should be with the same or less amount of sodium chloride or salt (Maluly et al., 2017).

The MSG controversy, when racism mixes with food

The restaurant industry, especially Chinese restaurants, are also big supporters of the usage of glutamate in cooking (Mouritsen & Styrbæk, 2014). This has led to a cultural association in Western society between the usage of glutamate and Chinese restaurants (Mouritsen & Styrbæk, 2014). Stemming from the same association was also the phenomenon known as the “Chinese restaurant syndrome” where a certain temporary hypersensitivity condition supposedly caused by eating food that was thought to be containing high amounts of MSG at Chinese restaurants. Originally the syndrome was described in a letter to the editor of The New England Journal of Medicine in the 1960s by Dr. Robert Ho Man Kwok. He mentioned the syndrome vaguely with symptoms including gradually radiating numbness, heart palpitations and thirst 15 to 20 minutes after consumption of the dish. He suggested a possible connection between the excessive combination of MSG and table salt. This was the beginning of the controversy that is still going on today.

DID YOU KNOW: 

Dr. Kwok in an interview with This American Life was revealed to be Dr. Howard Steel, a caucasian professor from the University of Maryland. However, the New England Journal of Medicine has yet to acknowledge that Dr. Howard Steel was the person who pen and sent the letter. The letter was sent due to a $10 dollar bet with a friend to see if he could be published in NEJM. He wrote the letter and rather than signing using his name, he choose Ho Man Kwok (an offensive pun for human crock). The doctor was horrified that the letter was published and unsuccessfully tried to get it retracted. Dr. Steel also tried to talk to many but none believe him that it was just a joke. ("668: The Long Fuse", 2019)

One of the most common complaints against MSG is that it can induce a feeling of thirst. While this could certainly be caused by the sodium within MSG, the amount of MSG (0.2 – 0.8% by weight in food) (Rogers, 2015) is often a lot smaller in comparison to salt (1.8% by weight in deep crispy pizza) ("How much salt are you eating?", n.d.) which are one of the main sodium contributors. Since the effect of MSG can cause food to actually taste saltier than it should, the food one is eating should contain even less salt than equivalent of one serving without MSG. MSG has yet to be shown to have effects on thirst. These thirsty urges could simply be from the high sodium chloride, or salt, content of Chinese food rather than MSG.

Many studies have been carried out on animal models such as rats for potential negative physiological and neurological effects of MSG (Hashem et al., 2012; Sharma et al., 2014). Many reviews however have also pointed out that due to the difference in glutamate metabolism of humans and the model animals, as well as the usage of glutamate often as food additive rather than direct consumption, many of the links to potential negative effects in humans in these studies are unclear (Beyreuther et al., 2007; Rogers, 2015; Zanfirescu et al., 2019). Studies in humans have so far shown no significant danger of MSG used as food additive to non-glutamate sensitive individuals (Zanfirescu et al., 2019). Therefore, the status of MSG as a safe food additive is still maintained by the FDA since 1958 and other international/national agencies and organizations.

DID YOU KNOW:

In rat neurological function, a recent study in 2014 studied a potential relationship between MSG and Alzheimer’s disease (Dief et al., 2014). The MSG treated rats were either consuming MSG solution of 10% orally a total amount of 2 g/kg body weight or provided with injection of 10% MSG solution with 4 g/kg body weight daily. The research was based on the idea that cerebral glutamate can cause neuronal shrinkage and apoptosis. However, the research has also found that no change in the glutamate content within the brain was detected in both treatments with oral and subcutaneous MSG. Even though there has been association between cyclic AMP-protein kinase and glutamate, without a clear cerebral glutamate response, the conclusion of the article linking glutamate to the increase in cyclic AMP-protein kinase is not straight forward (Rogers, 2015). 

Despite the controversy, MSG is still been used widely across the world without any problems. Glutamic acid being one of the most abundant non-essential amino acids of life, while glutamate is a vital component in neuro messaging (Briguglio et al., 2018; Lindemann, 2000), sensitivity or allergy to MSG from food is likely to be impossible. The symptoms related to the allegedly MSG allergy described as the “Chinese restaurant syndrome” can also be caused by consumption of too much sodium chloride, otherwise known as salt. Much of the current aversion altitude in western society to MSG despite advocated for by some of the most famous professional chefs has been suggested to not be from the supposed allergy but rather from possible underlying cultural sentiment against the exotic fast food (Mosby, 2009). In a report by 538, professor Brendan Nyhan of Dartmouth pointed out a possible cause that people just involuntarily association of bad feeling after eating Chinese food with MSG without investigating the actual causes ("How MSG Got A Bad Rap: Flawed Science And Xenophobia", n.d.) . These conclusions, once made, would be very hard to be replaced despite the availability of information that proves otherwise.

Glutamic acid being one of the most abundant non-essential amino acids of life, while glutamate is a vital component in neuro messaging (Briguglio et al., 2018; Lindemann, 2000), sensitivity or allergy to MSG from food is likely to be impossible.

Furthermore, even though the compound is widely used in the western processed food industry, known as additive 620 or 621 ("MSG in food", n.d.), the term MSG seems to carry a special stigma toward eastern cuisine (Mosby, 2009). This stigma could be observed through much of the reactions to “Chinese restaurant syndrome” at the time when “Dr. Kwok’s” letter was released focusing only on Chinese restaurants, describing their food with sneaky and hidden MSG (Mosby, 2009). There were campaigns demanding MSG usage should be limited not only in Chinese food but in other cuisines (Mosby, 2009). These sentiments were further amplified by the thought that, within Chinese cuisine, there were possible unproven consumption of meat that was deemed deviant and that MSG was used to hide it (Mosby, 2009). By appealing to the underlying fear and racial bias, with only inconclusive and anecdotal evidence, the ideas that MSG and in turn Chinese cooking should be avoided are still pervasive nowadays despite the compound being championed by celebrity chefs of modern cuisine like Heston Blumenthal and Grant Achatz.

While chef Blumenthal was uncertain about the healthiness of the common salt, he opposes the negative press of MSG (Malnick, 2014). At Cheltenham Literature Festival, he said that the compound is important to our taste buds and should not be ignored (Malnick, 2014). In an interview with Tasting Table, chef Achatz who traveled with his own stash of MSG powder was also confident of the role of MSG in good food, mentioning that “It's really no different than, say, using nitrates to cure sausage or pink salt to preserve boudin blanc.” ("Grant Achatz and MSG", 2013)

For the Asian chefs who have been growing up eating home cook meal with MSG, the idea that MSG causing serious health problems is totally nonsense. As chef Roy Choi had to say, "I grew up on it by the buckets. Go to any Asian home: It's there next to the sugar and salt. It's a flavor that's ingrained in my soul." ("Grant Achatz and MSG", 2013). And one of the most vocal supporters of MSG, chef David Chang, has to say about the important of MSG in cooking, "It's the MSG. That's why everyone is so enamoured with Asian flavours. It has that punch that we don't find in other foods." (Akhtar, 2013)

So, to finish this fresh new look at MSG, it can be concluded that with no direct evidence of health-related problems stemming from MSG as food flavor enhancer, the scientific consensus is that MSG is safe in the way it is currently being used for human consumption as 0.2-0.8% in weight of food. In fact, monosodium glutamate (MSG) can be used to reduce your consumption of sodium chloride (table salt) in foods while you cook (Maluly et al., 2017), while adding a fabulous umami flavor to your dishes. So there you go! Another positive to this amino acid salt!

References

668: The Long Fuse. (2019, February 16). This American Life. https://www.thisamericanlife.org/668/transcript

Akhtar, K. (2013, December 9). MSG finding its way back to restaurant menus. CBC. https://www.cbc.ca/news/canada/msg-finding-its-way-back-to-restaurant-menus-1.2457140

Beyreuther, K., Biesalski, H. K., Fernstrom, J. D., Grimm, P., Hammes, W. P., Heinemann, U., Kempski, O., Stehle, P., Steinhart, H., & Walker, R. (2007). Consensus meeting: Monosodium glutamate – an update. European Journal of Clinical Nutrition, 61(3), 304–313. https://doi.org/10.1038/sj.ejcn.1602526

Briguglio, M., Dell’Osso, B., Panzica, G., Malgaroli, A., Banfi, G., Zanaboni Dina, C., Galentino, R., & Porta, M. (2018). Dietary Neurotransmitters: A Narrative Review on Current Knowledge. Nutrients, 10(5). https://doi.org/10.3390/nu10050591

Chinese-Restaurant Syndrome. (1968). New England Journal of Medicine, 278(14), 796–796. https://doi.org/10.1056/NEJM196804042781419

Dief, A. E., Kamha, E. S., Baraka, A. M., & Elshorbagy, A. K. (2014). Monosodium glutamate neurotoxicity increases beta amyloid in the rat hippocampus: A potential role for cyclic AMP protein kinase. NeuroToxicology, 42, 76–82. https://doi.org/10.1016/j.neuro.2014.04.003

Grant Achatz and MSG. (2013, December 6). Tasting Table. https://www.tastingtable.com/cook/national/Grant-Achatz-and-MSG

Hashem, H. E., El-Din Safwat, M. D., & Algaidi, S. (2012). The effect of monosodium glutamate on the cerebellar cortex of male albino rats and the protective role of vitamin C (histological and immunohistochemical study). Journal of Molecular Histology, 43(2), 179–186. https://doi.org/10.1007/s10735-011-9380-0

How MSG Got A Bad Rap: Flawed Science And Xenophobia | FiveThirtyEight. (n.d.). Retrieved December 22, 2019, from https://fivethirtyeight.com/features/how-msg-got-a-bad-rap-flawed-science-and-xenophobia/

How much salt are you eating? (n.d.). Retrieved December 20, 2019, from https://www.safefood.eu/How-much-salt-are-you-eating

Hubbard, J. A., & Binder, D. K. (2016). Chapter 9—Glutamate Metabolism. In J. A. Hubbard & D. K. Binder (Eds.), Astrocytes and Epilepsy (pp. 197–224). Academic Press. https://doi.org/10.1016/B978-0-12-802401-0.00009-0

Lindemann, B. (2000). A taste for umami. Nature Neuroscience, 3(2), 99–100. https://doi.org/10.1038/72153

Malnick, E. (2014, October 12). Heston Blumenthal says idea MSG is bad for you is “old wives tale.” https://www.telegraph.co.uk/foodanddrink/foodanddrinknews/11156357/Heston-Blumenthal-says-idea-MSG-is-bad-for-you-is-old-wives-tale.html

Maluly, H. D. B., Arisseto‐Bragotto, A. P., & Reyes, F. G. R. (2017). Monosodium glutamate as a tool to reduce sodium in foodstuffs: Technological and safety aspects. Food Science & Nutrition, 5(6), 1039–1048. https://doi.org/10.1002/fsn3.499

Mosby, I. (2009). ‘That Won-Ton Soup Headache’: The Chinese Restaurant Syndrome, MSG and the Making of American Food, 1968–1980. Social History of Medicine, 22(1), 133–151. https://doi.org/10.1093/shm/hkn098

Mouritsen, O., & Styrbæk, K. (2014). Umami, Unlocking the Secrets of the Fifth Taste. Columbia University Press. https://doi.org/10.7312/mour16890

MSG in food. (n.d.). Retrieved January 19, 2020, from https://www.foodstandards.gov.au/consumer/additives/msg/Pages/default.aspx

Osawa, Y. (2012). Glutamate Perception, Soup Stock, and the Concept of Umami: The Ethnography, Food Ecology, and History of Dashi in Japan. Ecology of Food and Nutrition, 51(4), 329–345. https://doi.org/10.1080/03670244.2012.691389

Otsuka, S. (1998). Umami in Japan, Korea, and Southeast Asia. Food Reviews International, 14(2–3), 247–256. https://doi.org/10.1080/87559129809541159

PubChem. (n.d.). Glutamic acid. Retrieved January 19, 2020, from https://pubchem.ncbi.nlm.nih.gov/compound/33032

Rogers, M. D. (2015). Commentary on “Monosodium glutamate neurotoxicity increases beta amyloid in the rat hippocampus: A potential role for cyclic AMP protein kinase” (Dief et al., 2014). NeuroToxicology, 50, 179–180. https://doi.org/10.1016/j.neuro.2015.06.003

Sharma, A., Wongkham, C., Prasongwattana, V., Boonnate, P., Thanan, R., Reungjui, S., & Cha’on, U. (2014). Proteomic analysis of kidney in rats chronically exposed to monosodium glutamate. PLoS ONE, 9(12), e116233. https://doi.org/10.1371/journal.pone.0116233

Suess, B., Festring, D., & Hofmann, T. (2015). 15—Umami compounds and taste enhancers. In J. K. Parker, J. S. Elmore, & L. Methven (Eds.), Flavour Development, Analysis and Perception in Food and Beverages (pp. 331–351). Woodhead Publishing. https://doi.org/10.1016/B978-1-78242-103-0.00015-1

Tamang, J. P., Kailasapathy, K., & Kailasapathy, K. (2010). Fermented Foods and Beverages of the World. CRC Press. https://doi.org/10.1201/EBK1420094954

Vickery, H. Bradford., & Schmidt, C. L. A. (1931). The History of the Discovery of the Amino Acids. Chemical Reviews, 9(2), 169–318. https://doi.org/10.1021/cr60033a001

Williams, A. C., & Hill, L. J. (2017). Meat and Nicotinamide: A Causal Role in Human Evolution, History, and Demographics. International Journal of Tryptophan Research : IJTR, 10. https://doi.org/10.1177/1178646917704661

Yamaguchi, S., & Ninomiya, K. (1998). What is umami? Food Reviews International, 14(2–3), 123–138. https://doi.org/10.1080/87559129809541155

Yoshida, Y. (1998). Umami taste and traditional seasonings. Food Reviews International, 14(2–3), 213–246. https://doi.org/10.1080/87559129809541158

Zanfirescu, A., Ungurianu, A., Tsatsakis, A. M., Nițulescu, G. M., Kouretas, D., Veskoukis, A., Tsoukalas, D., Engin, A. B., Aschner, M., & Margină, D. (2019). A Review of the Alleged Health Hazards of Monosodium Glutamate. Comprehensive Reviews in Food Science and Food Safety, 18(4), 1111–1134. https://doi.org/10.1111/1541-4337.12448

Introducing the Food Science Series, through these articles, we will explore different aspects of food science as well as the people investigating within these fields.

Water, barley, hops, and yeast, the quadfecta necessary for brewing of beer, one of the most important food inventions of the human civilization in over 5000 years (Curry, Andrew, 2017). However, despite the long history, our understanding of how yeast and water combine with the proteins and carbohydrates found in barley can produce the various textures and flavors to the beverage as we know it today is still limited. In this episode, we will explore a little bit of science that is currently being used for studying the connection between these elements with a colleague of ours, Mr. Edward Kerr, a current PhD candidate at the School of Chemistry and Molecular Bioscience (SCMB), The University of Queensland (UQ).

What is your work? What do you do? And what is the scope of your project?

I’m doing a PhD in Biochemistry, focusing on brewing biochemistry. I use proteomics and metabolomics to understand and optimise the brewing process. My project also involves using microbiology techniques to isolate and characterise wild yeast from Brisbane for beer brewing.

Beer yeast or Saccharomyces cerevisiae was originally described in 1838 by Dr. Franz Julius Ferdinand Meyen (Meyen, 1839). S. cerevisiae has been isolated and developed specifically for their ability to convert sugar from barley into alcohol for beer production. Contamination with other yeast strains in commercial production often corrupts the process and the expected taste and texture profile of the beer. Specific brewing apparatuses have been used by the industry to minimize contamination from wild yeast in the environment since 1886 (Stewart, 2017). Nonetheless, when the aim is to achieve new flavor profiles for beer production, more often than not, wild yeast strains are used alongside traditional and non-traditional brewing components.

For this project, Ed has approached a local brewery. The Newstead Brewery, located in Brisbane, Queensland, Australia, for a collaboration for collecting and characterizing wild yeasts for production of beer. The specific aim is to produce more interesting flavors as well as demonstrating the complexity of brewing when wild yeast from the environment. The knowledge gained from the adaptation as well as optimization of the commercial brewing process for wild yeast could have potential for changes as well as improvements in the current brewing process, that uses domesticated yeast, for better beer production.

What is proteomics? How is it used in your project? And How often is it used in the beer industry?

Proteomics is the study of the proteome, which is an entire set of expressed proteins within a system. We use proteomes to identify and measure the changes in protein abundance throughout the brewing process. The brewing process is based on malted Malting is the germination process where digestion enzymes are released by the grain to convert complex carbohydrates into simpler forms. barley seeds and yeast, therefore barley and yeast proteins that are present and change throughout the process. The change in the proteome throughout the brewing process can affect the final product. With different proteins having different effects on beer and taste. Proteomics has been used previously in the brewing field, most research that has used proteomics relies on older techniques.

The traditional brewing process includes the breaking down of complex carbohydrates into a yeast-compatible food resource within a solution (Willaert, 2006). This mixture is called the wort. Yeast fermentation process would convert the available nutrient to alcohol and other flavoring byproducts (Willaert, 2006). Using a proteomic technique such as mass spectrometry on samples collected during the process, it is possible to follow and identify the changes within the proteome of the mixture through each step in each sample. 

Current proteomic processes are not utilized in large scale beer manufacturing due to its cost. Manufacturers right now are only looking at what is there, and not at what are the specific differences or changes during the beer process. In a previous study, Ed utilized proteomics for the investigation of the proteome changes from the beer brewing mashing Mashing is the process to dissolve sugars and proteins from the grain into a solution. process (Kerr, Caboche, & Schulz, 2019). The result of this study showed that early in the mashing process some of the protein population within the solution, are cut up by barley proteases (Kerr et al., 2019). These protein fragments are vulnerable to the high temperatures used during the mashing process and precipitated (Kerr et al., 2019). This further demonstrated the complexity of brewing, where the protein solubility that affects the flavor profile can in turn be affected by various factors ranging from brewing parameters to the specific characteristics of the different barley varieties (Kerr et al., 2019).

How different are the fermentation processes in different types of beers? How important are they to the differences between the different types of beers?

There are generally two fermentation types: 

1) Ale fermentation or top-fermenting: which uses strains of Saccharomyces cerevisiae and fermentation occurs at ~22 C. 

2) Lager fermentation or bottom-fermenting: which uses strains of Saccharomyces pastorianus and fermentation occurs at colder temperatures.

Other than this, there are strains and species of yeast from the environment (A.K.A, wild yeast) or other types of yeast,  that can be used to spontaneously ferment that do not follow this Ale/Lager fermentation system.

Study of S. pastorianus genome has revealed that this organism is a domesticated hybrid strain of S. eubayanus and S. cerevisiae (Libkind et al., 2011). Different to its wild ancestor, S. pastorianus gain the ability from S. cerevisiae to process disaccharide maltose which is highly abundant in wort (Libkind et al., 2011).

Between different beers, people used to say that water is a differentiating factor in beer brewing, in modern beer production, it is actually the element that introduces the least variability to the process, due to the usage of purified water in modern beer brewing with minerals being add at a later stage and other chemical elements. Commercial yeasts that are in use, are often produced by the same company. This practice does not provide with enough variability to the brewing processes of different beer types. It is often the malt, which can vary a lot between regions as well as the production process, that makes the difference between different beers. Currently, in the lab, there is a study looking at the difference in soluble protein content within the malt and yeast, comparing them between brewing styles, breweries, and regions.

From the analysis of your proteomics data, what potential impact do you think it can have on beer production? Have any of your discoveries led to any changes in your fermentation process? 

Proteomics specifically has not led to any direct changes in the brewing process. We are working on using proteomics to gain and improve screening for new barley varieties for brewing that are disease resistant and higher quality.

Besides different yeast strains giving different flavoring compounds as well as alcohol content, different barley varieties would also have different amounts of available sugars in wort for fermentation as well as flavor compounds. The usage of different varieties could also offer higher or lower level of alcohol and different flavor profiles.

What are the different beers that you are currently working with? How different are they from the production and proteomics perspective?

We are working on wild yeast, which typically are not used by commercial breweries. Fermenting with these yeasts is difficult and poorly understood. We have had great difficulties taking yeast and upscaling the production from a small 30 mL scale in a lab to 1000 L in a brewery.

We haven’t used proteomics yet to help with these industrial challenges but it is on our list!   

The current brewing process has been highly optimized for the use of traditional brewer’s yeast. Similar to what we have discussed above, different brewing yeasts would ferment optimally at different temperatures. Wild yeast suppose a different challenge, partly because they are not well understood and have not been characterized. They might require a different configuration entirely for scalability to be effective in an industrial setting.

What results have you achieved with them so far?

We are getting close to being able to produce commercial batches of our yeast with our industry partner Newstead Brewing Co., but further from these using proteomics and microbiology we have really gained an understanding of the entire brewing process using new modern biochemical techniques that are not applied to this field as of yet.

What do you think is the most interesting aspect of modern beer production?

Definitely the people. Everyone in craft/independent brewing are helpful, lovely, and genuinely interested in brewing beer and providing a unique and interesting beer.

Brisbane, Queensland, Australia - 25^th, November, 2019

Bibliography

Curry, Andrew. (2017, January 17). Our 9,000-Year Love Affair With Booze. Retrieved December 13, 2019, from National Geographic website: https://www.nationalgeographic.com/magazine/2017/02/alcohol-discovery-addiction-booze-human-culture/

Kerr, E. D., Caboche, C. H., & Schulz, B. L. (2019). Post-translational modifications drive protein stability to control the dynamic beer brewing proteome. Molecular & Cellular Proteomics, mcp.RA119.001526. https://doi.org/10.1074/mcp.RA119.001526

Libkind, D., Hittinger, C. T., Valério, E., Gonçalves, C., Dover, J., Johnston, M., … Sampaio, J. P. (2011). Microbe domestication and the identification of the wild genetic stock of lager-brewing yeast. Proceedings of the National Academy of Sciences, 108(35), 14539. https://doi.org/10.1073/pnas.1105430108

Meyen, F. J. F. (1839). Jahresbericht über die Resultate der Arbeiten im Felde der physiologischen Botanik von dem Jahre 1837. Nicolai.

Stewart, G. G. (2017). History of Brewing and Distilling Yeast. In G. G. Stewart (Ed.), Brewing and Distilling Yeasts (pp. 11–36). https://doi.org/10.1007/978-3-319-69126-8_2

Willaert, R. (2006). The Beer Brewing Process: Wort Production and Beer Fermentation. In Handbook of Food Products Manufacturing (pp. 443–506). https://doi.org/10.1002/9780470113554.ch20

Or are we just being over cautious?

Fair enough we know this trend is actually not that new. This all started back in May 2017, when renowned U.S. chef Alton Brown posted an image on his Instagram account of him baking meatballs in egg cartons.  It managed to make an impact on how people, otherwise known as foodies, cook their meatballs. It’s now 2019, and the hack is still being reposted, so it caught our eye. So to start this blog, we decided to verify it against facts, using our science background and our joint passion for food. Let’s start by introducing all of us to the original post.

After this original post, sites like: BuzzFeed (https://www.buzzfeed.com/jesseszewczyk/alton-brown-meatball-cooking-hack), Delish (https://www.delish.com/restaurants/news/a53415/alton-browns-hack-for-meatballs/), Everybody craves (http://craves.everybodyshops.com/alton-browns-genius-meatball-baking-hack-youll-want-to-copy/), among others, broke the news to the rest of the internet (those that do not have an Instagram account). Where the base audience is much wider and can reach to other demographics. This was our cue to add some facts to your life that will make you think twice when you read about “genius hacks” like this one, and would like to try giving them a go at home.

“… in other countries, especially in Europe, the practice of washing eggs is actually discouraged.”

To examine this particular trend, we will take a look at each individual element. Let us start with the egg cartons. In many countries, like the US, eggs are often washed before being transferred into a container for transport to the market. These washes are used to remove harmful pathogens that can infect the eggs and those in contact with them. However, in other countries, especially in Europe, the practice of washing eggs is actually discouraged (“EUR-Lex—32008R0589—EN - EUR-Lex,” n.d.). Why would this be, you may ask? To answer this question, let us start with a brief overview into the structure of the eggshell.

Structure of the eggshell 

The structure of the eggshell starts with a fibrous membrane layer (Chien, Hincke, & McKee, 2009). This layer has a matrix of proteins that functions as a guide for the deposition of calcium salts into the fibrous membrane, resulting in the hard shell that all eggs have and that we are familiar with (Chien et al., 2009). In order to maintain respiratory function with the outside environment, this hard shell is porous (Tyler, 1945).

For commercial food production, the European Council regulation on egg production, No 589/2008 of 23 June 2008, actively discourages the practice because it damages the eggshell allowing contamination to enter the egg.

Beyond this, there is another thin but very important layer of organic matter called the cuticle (Vadehra, Baker, & Naylor, 1970) Its role is crucial for the chick’s survival because it serves as the initial barrier against infection through the hard shell (Mikšík, Ergang, & Pácha, 2014), and here lies the main reasoning against egg washing.

For commercial food production, the European Council regulation on egg production, actively discourages the practice because it damages the eggshell allowing contamination to enter the egg (“EUR-Lex—32008R0589—EN - EUR-Lex,” n.d.). While egg washing can effectively remove pathogens from the egg surface, it leaves the egg much more vulnerable than before because of the damage sustained in the cuticle membrane (Samiullah et al., 2013; Vadehra et al., 1970). This regulation is supported by decades of studies into the practice of washing and rates of trans-shell infection (Vadehra et al., 1970).

Due to the possibility of contamination during the storage and transportation process,… egg containers are considered single-used item by the United States Department of Agriculture (USDA).

In countries where the practice is encouraged, eggs are washed and then immediately put into cold chain storage (Gole et al., 2014; “Shell Eggs from Farm to Table,” n.d.). The emphasis on cold chain storage here is to prevent bacterial growth on the now damaged cuticle. The washing process grants pathogens the ability to cross the cuticle membrane easily (Vadehra et al., 1970). The poultry industry recognizes that eggs can potentially become contaminated during the transportation and storage process, and egg containers are considered single-used items by the United States Department of Agriculture (USDA) (“Meat and Poultry Packaging Materials,” n.d.). However, the container is not sterile. It can have pathogens, bacteria or fungus, from  the egg surface, the transportation process, or the storage environment (Grizard, Dini-Andreote, Tieleman, & Salles, 2014; Soni, Oey, Silcock, & Bremer, 2016; Välsänen, Mentu, & Salkinoja‐Salonen, 1991). The containers themselves are considered an artificial protective layer that is used to protect the eggs from physical damage and further visible contamination. 

Egg containers, aka, egg cartons

Usually made from either plastic, styrofoam, or carton paper, these containers are commonly used and shaped in a way that provides each individual egg with protection against the environment and each other (“Egg carton,” n.d.). For this discussion, we will focus on the paper carton container.

Making a carton paper egg container is a 4-step process. First, the material used for the carton, usually recycled paper and carton, is processed into smooth pulp and corrected in size. The pulp is stored in pools of slurry mixture. This is followed by the molding step, where the pulp is deposited into molds. While a vacuum system forces the pulp into the appropriate molding form, a desiccating process also takes place in order to remove wet products from the formed container shape. The container is then taken out of the molding box for further drying. The drying process can be active drying with high heat or natural air drying.  Finally, when the containers are dried, they are pressed together into the final carton shape that we all know (“Egg Carton Manufacturing Process | Paper Egg Box Making Process,” 2018).

Besides the already discussed cross contamination, flammability of this non-cooking paper material is also a possibility.

As the process above has indicated, the paper used for food packaging is already highly processed and naturally degradable which means that it can be a source of microorganisms (Välsänen et al., 1991). This could even occur during the production process of the containers themselves. Because the paper pulp is stored as slurry pools, this process could potentially also introduce fungal pathogens besides bacteria into the egg carton. 

If the drying process was not done under high temperature, the container is very likely to still harbor pathogens from the original recycled material or the processing environment (Välsänen et al., 1991).  With a high temperature drying process, the surviving microorganisms are often spore-formers identified from the source material used to create the container (Välsänen et al., 1991). These pathogens are often thermoresistant and some can even grow at 4°C. Besides the thermoresistant pathogens, paper is also a porous material which can hide pathogens and reduce effectiveness of conventional sanitization methods. This points to a high possibility of contamination of ingredients stored within this type of paper containers by dormant pathogens (i.e., spores or spore forming organisms) that can survive the production process. 

To continue with the discussion at hand, this would mean the contamination of the meatballs, that we would cook in these carton containers. Besides  cross contamination, flammability of this non-cooking paper material is also a concern. The autoignition point, or combustion temperature without an external flame, of normal paper ranges within 218 to 246 °C, depending on the type used (“T.C. Forensic: Article 10—PHYSICAL CONSTANTS FOR INVESTIGATORS,” n.d.). Considering the type of paper used in common egg container (compressed paper to make the cartons), it would make sense for the temperature to be in the lower half of the autoignition range. 

A potential hidden danger for cooking with non-cooking grade paper material is from the possible temperature inaccuracy of home ovens. You could think that you are cooking at the set temperature, but the oven could be at a higher temperature. Depending on the type of oven, gas or electric, if there is a spark involved in the ignition process of the oven paper can catch fire at an even lower temperature. Therefore, there is a possibility that the common meatball baking temperature of around 400° F (or 205° C) could cause the egg carton to start burning inside the oven.

Meat cooking and meat pathogens

Another factor that adds up to the danger, is the selective evolution caused by the constant presence of low antibiotic concentration from animal waste and feeds runoff.

So, we have come this far in the discussion of this hot topic. Now let us get into matters with how this trend combines not only the possible pathogens from the eggs and the environment (storage of the carton and carton processing), but also risks from meat. We could potentially be looking at a wide range of dangerous pathogens including Salmonella spp., Campylobacter and E. coli. As in the case of meat, many of these organisms can be introduced in different steps from the farm to processing and cooking (Currie et al., 2007; SARTZ et al., 2008). 

In the farm, sources of contamination include  the soil, animal feed, fecal matter, pests, and the animals themselves, as well as environmental contamination (Mor-Mur & Yuste, 2009). Another factor that adds up to the danger, is the selective evolution caused by the constant presence of low antibiotic concentration from animal waste and feeds runoff. That has increased the presence of dangerous antibiotic resistant strains that can contaminate our food (Khachatourians, 1998; Zhang et al., 2014). It is more important than ever to maintain a safe food preparation and cooking practices that reduce our exposure to these pathogens. Antibiotic resistant Salmonella and E. coli, e.g. Salmonella enterica subsp. Enterica serovar Typhimurium (DiMarzio, Shariat, Kariyawasam, Barrangou, & Dudley, 2013) and ESBL-producing Extended-Spectrum-β-Lactamase producing ability gives the pathogen resistance to the most common antibiotic type, β-Lactam. E. coli O64 (Dutta et al., 2013),  can nullify most of our antibiotic arsenal, leading to longer and more damaging infections (Rasheed, Thajuddin, Ahamed, Teklemariam, & Jamil, 2014; V. T. Nair, Venkitanarayanan, & Kollanoor Johny, 2018). 

Due to the mass production nature of commercial food production, contamination of food can spread quickly and extensively through the production chain. Besides the equipment itself, aerosols within the facility are a big source of contaminants due to centralized industrial cooling systems (Mor-Mur & Yuste, 2009). The food industry has developed decontamination processes involving multiple approaches such as steam, vacuum and antimicrobial washes. However, there have also been reports of pathogens surviving the process that also acquired extra resistance against the utilized methods (Capita & Alonso-Calleja, 2013). This further emphasizes the importance of proper sanitization and hygienic food processing as the main microbial control method (Holah, 1992)..

Beyond the processing facility, if all has gone well during transportation, there is the risk of post-process contamination during storage (Bantawa, Rai, Subba Limbu, & Khanal, 2018). Incorrect pest management and control can provide the ideal environment for pests that carry dangerous pathogens to multiply (Boey, Shiokawa, & Rajeev, 2019, “Pests,” n.d.).

One of the most common pests are rats. They are often carriers of many dangerous diseases. A major disease-causing pathogen that can be spread by rats is Leptospira spp. (Boey, Shiokawa, & Rajeev, 2019). Often, the pathogens are spread through the carrier’s urine, in this case, rat urine. These pathogens can contaminate water, soil, or containers (Muñoz-Zanzi, Mason, Encina, Astroza, & Romero, 2014). In this scenario a possible contamination point could also be from contaminated carton containers during storage. Warehouse storage conditions can range from low to little light and dampness. These alongside with the natural carton porosity can provide favourable conditions for the pathogen to survive on their. Leptospira, in case you were not aware, can cause serious diseases Most known diseases according to the European Centre for Disease Prevention and Control: Weil’s Syndrome and Severe Pulmonary Haemorrhagic Syndromes diseases and lead to death if left untreated (“Leptospirosis | CDC,” 2019).

We mentioned how the egg cartons themselves can be contaminated. Now let us focus on how food itself, in this case the meat. Meat can be contaminated during processing. After food has already been contaminated by pathogens, these produce toxins. These toxins are also part of the mechanisms of infection of these pathogens (Martinović, Andjelković, Gajdošik, Rešetar, & Josić, 2016).

Bacillus cereus, more specifically B. cereus sensu stricto, is a common food borne pathogen that can be found contaminating raw meat or can be introduced in meat products through contaminated meat additives (Gdoura-Ben Amor et al., 2018; Güven, Mutlu, & Avci, 2006; Smith, Berrang, Feldner, Phillips, & Meinersmann, 2004; Tewari, Singh, & Singh, 2015). The pathogen is particularly common in a wide variety of foods and food products due to its ability to create an endospore that grant it the ability to grow in a wide range of environmental conditions together with its tolerance to common heat sterilization process (Foegeding & Berry, 1997; Gdoura-Ben Amor et al., 2018; Harmon & Kautter, 1991; Soares, Kabuki, & Kuaye, 2012). In meat, it has been reported that the germination of these inoculated endospores can be observed within a temperature range of  10 to 30 °C (Soares et al., 2012). Furthermore, the bacteria also has the ability to form biofilms on industrial surfaces increasing its ability to spread within the food processing chain (Majed, Faille, Kallassy, & Gohar, 2016). The pathogen produces a preformed emetic toxin and several other enterotoxins (Granum & Lund, 1997). The emetic toxin cannot be removed by cooking and can cause nausea and vomiting (Granum & Lund, 1997). Besides the preformed toxins, the pathogen also produces a collection of enterotoxins that can cause diarrhea (Granum & Lund, 1997). For B. cereus, a certain level of bacterial load is allowed (<10³cfu/g or ml), however due to the prevalence of the organism in many steps of food processing, the potential of further contamination within the process as well as the growth potential of the organism make it important to emphasize strict sanitization for prevention of food poisoning (Gdoura-Ben Amor et al., 2018).

Similar to the pathogens, some of the toxins, specifically preformed toxins, can be persistent and require different approaches for decontamination and detoxification. These processes range from heat to gas plasma Gas plasma treatment of food is a process where gaseous chemical that can produce free radicals are allowed to permeate the object. An electrical field would then be used to activate the gases and create radical species that would inactivate the toxin as well as destroying the microorganisms. treatment (Karlovsky et al., 2016). However, the presence of the toxin means that unhygienic practices were present  somewhere along the production and process chain. This should warrant caution to any further consumption of the food.

Decision Time

If the carton is already contaminated, it will potentially contaminate the meat.

So far, we have presented to you all the facts that encompass this trend as well as all the potential hiccups that could pose a threat to your health.

With all this knowledge at hand, this trend does seem to pose a potential health hazard because, as we have explained, egg cartons are not made for meatball cooking. They were conceived as a transport and storage device for eggs and so does their production and storage. If the carton is already contaminated, it will potentially contaminate the meat. Some pathogens like E. coli, have the ability to double every 17-20 minutes, for example the strain O157:H7, has a low infectious dose, it can cause illness with exposure to only 20 organisms (Guerini, Arthur, Shackelford, & Koohmaraie, 2006; “Water Treatability Database,” n.d.). Because of their material, carton, there is also the potential of fire and you could say: “but hey I do not have a gas oven for there to be an open flame, I have an electric oven, what about that?” From what we read above, dry heat from an electric oven can also autoignite the paper from the carton. Next time that a trend does come by, think about all the repercussions that it might have and do not let the trends scramble you around!

What if?IMPORTANT DISCLAIMER: We are not endorsing the use of any of these techniques for sanitization of egg cartons at home, we are merely pointing them out for informative reasons.

If despite all of this, we are discussing, you are still willing to use the egg cartons as a cooking device, according to a review on inactivation technology for Bacillus sp. spore formers in food, there are several options that one may use for sanitization of these containers:

Heat-based. Knowing the autoignition point of paper, it is possible to apply a dry heat method at high temperature (121° C) for 1 hour (Soni et al., 2016).

UV-based. Excimer UV Excimer refers to dimer where the components only bond in excited state. The UV radiation in this case is the resulting energy emission when the components return to ground state and immediately dissociate. radiation has been shown to be able to reduce the number of active spores significantly without applying too much heat into the object. While it is not recommended for actual food, excimer UV radiation treatment works best for surface of cartons and packages, which is relevant for egg carton containers (Soni et al., 2016). The actual problem with this alternative is the fact that conventional households do not have UV emitting devices, making it hard to implement. 

Pressure-based. This is an approach where compression can cause damage to the pathogen proteome and thus kill it. One way that pressure is currently used  is in combination with heat and/or UV based processing (Soni et al., 2016). This powerful combinatory approach may be able to sanitize our carton container but is also highly unlikely to be practical for home usage.

Bibliography

Bantawa, K., Rai, K., Subba Limbu, D., & Khanal, H. (2018). Food-borne bacterial pathogens in marketed raw meat of Dharan, eastern Nepal. BMC Research Notes, 11. https://doi.org/10.1186/s13104-018-3722-x

Boey, K., Shiokawa, K., & Rajeev, S. (2019). Leptospira infection in rats: A literature review of global prevalence and distribution. PLOS Neglected Tropical Diseases, 13(8), e0007499. https://doi.org/10.1371/journal.pntd.0007499

Capita, R., & Alonso-Calleja, C. (2013). Antibiotic-resistant bacteria: A challenge for the food industry. Critical Reviews in Food Science and Nutrition, 53(1), 11–48. https://doi.org/10.1080/10408398.2010.519837

Chien, Y.-C., Hincke, M. T., & McKee, M. D. (2009). Avian Eggshell Structure and Osteopontin. Cells Tissues Organs, 189(1–4), 38–43. https://doi.org/10.1159/000151374

Currie, A., Macdonald, J., Ellis, A., Siushansian, J., Chui, L., Charlebois, M., … Ng, L.-K. (2007). Outbreak of Escherichia coli O157:H7 Infections Associated with Consumption of Beef Donair. Journal of Food Protection, 70(6), 1483–1488. https://doi.org/10.4315/0362-028X-70.6.1483

DiMarzio, M., Shariat, N., Kariyawasam, S., Barrangou, R., & Dudley, E. G. (2013). Antibiotic Resistance in Salmonella enterica Serovar Typhimurium Associates with CRISPR Sequence Type. Antimicrobial Agents and Chemotherapy, 57(9), 4282–4289. https://doi.org/10.1128/AAC.00913-13

Dutta, T. K., Warjri, I., Roychoudhury, P., Lalzampuia, H., Samanta, I., Joardar, S. N., … Chandra, R. (2013). Extended-Spectrum-β-Lactamase-Producing Escherichia coli Isolate Possessing the Shiga Toxin Gene (stx1) Belonging to the O64 Serogroup Associated with Human Disease in India. Journal of Clinical Microbiology, 51(6), 2008–2009. https://doi.org/10.1128/JCM.00575-13

Egg carton. (n.d.). Retrieved October 18, 2019, from Diffpack website: http://www.diffpack.com/egg-carton/

Egg Carton Manufacturing Process | Paper Egg Box Making Process. (2018, February 1). Retrieved October 18, 2019, from Beston Machinery website: https://bestoneggtraymachine.com/uniqueness-egg-carton-manufacturing-process/

EUR-Lex—32008R0589—EN - EUR-Lex. (n.d.). Retrieved October 10, 2019, from https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32008R0589

Foegeding, P. M., & Berry, E. D. (1997). Cold Temperature Growth of Clinical and Food Isolates of Bacillus cereus. Journal of Food Protection, 60(10), 1256–1258. https://doi.org/10.4315/0362-028X-60.10.1256

Gdoura-Ben Amor, M., Siala, M., Zayani, M., Grosset, N., Smaoui, S., Messadi-Akrout, F., … Gdoura, R. (2018). Isolation, Identification, Prevalence, and Genetic Diversity of Bacillus cereus Group Bacteria From Different Foodstuffs in Tunisia. Frontiers in Microbiology, 9. https://doi.org/10.3389/fmicb.2018.00447

Gole, V. C., Chousalkar, K. K., Roberts, J. R., Sexton, M., May, D., Tan, J., & Kiermeier, A. (2014). Effect of Egg Washing and Correlation between Eggshell Characteristics and Egg Penetration by Various Salmonella Typhimurium Strains. PLOS ONE, 9(3), e90987. https://doi.org/10.1371/journal.pone.0090987

Granum, P. E., & Lund, T. (1997). Bacillus cereus and its food poisoning toxins. FEMS Microbiology Letters, 157(2), 223–228. https://doi.org/10.1111/j.1574-6968.1997.tb12776.x

Grizard, S., Dini-Andreote, F., Tieleman, B. I., & Salles, J. F. (2014). Dynamics of bacterial and fungal communities associated with eggshells during incubation. Ecology and Evolution, 4(7), 1140–1157. https://doi.org/10.1002/ece3.1011

Guerini, M. N., Arthur, T. M., Shackelford, S. D., & Koohmaraie, M. (2006). Evaluation of Escherichia coli O157:H7 growth media for use in test-and-hold procedures for ground beef processing. Journal of Food Protection, 69(5), 1007–1011. https://doi.org/10.4315/0362-028x-69.5.1007

Güven, K., Mutlu, M. B., & Avci, Ö. (2006). Incidence and Characterization of Bacillus Cereus in Meat and Meat Products Consumed in Turkey. Journal of Food Safety, 26(1), 30–40. https://doi.org/10.1111/j.1745-4565.2005.00031.x

Harmon, S. M., & Kautter, D. A. (1991). Incidence and Growth Potential of Bacillus cereus in Ready-to-Serve Foods. Journal of Food Protection, 54(5), 372–374. https://doi.org/10.4315/0362-028X-54.5.372

Holah, J. T. (1992). Industrial Monitoring: Hygiene in Food Processing. In L. F. Melo, T. R. Bott, M. Fletcher, & B. Capdeville (Eds.), Biofilms—Science and Technology (pp. 645–659). https://doi.org/10.1007/978-94-011-1824-8_57

Karlovsky, P., Suman, M., Berthiller, F., De Meester, J., Eisenbrand, G., Perrin, I., … Dussort, P. (2016). Impact of food processing and detoxification treatments on mycotoxin contamination. Mycotoxin Research, 32(4), 179–205. https://doi.org/10.1007/s12550-016-0257-7

Khachatourians, G. G. (1998). Agricultural use of antibiotics and the evolution and transfer of anitbiotic-resistant bacteria. Canadian Medical Association. Journal: CMAJ; Ottawa, 159(9), 1129–1136.

Leptospirosis | CDC. (2019, March 13). Retrieved October 31, 2019, from https://www.cdc.gov/leptospirosis/index.html

Majed, R., Faille, C., Kallassy, M., & Gohar, M. (2016). Bacillus cereus Biofilms—Same, Only Different. Frontiers in Microbiology, 7. https://doi.org/10.3389/fmicb.2016.01054

Martinović, T., Andjelković, U., Gajdošik, M. Š., Rešetar, D., & Josić, D. (2016). Foodborne pathogens and their toxins. Journal of Proteomics, 147, 226–235. https://doi.org/10.1016/j.jprot.2016.04.029

Meat and Poultry Packaging Materials. (n.d.). Retrieved October 18, 2019, from https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/safe-food-handling/packaging-materials/meat-poultry-packaging-materials

Mikšík, I., Ergang, P., & Pácha, J. (2014). Proteomic analysis of chicken eggshell cuticle membrane layer. Analytical and Bioanalytical Chemistry, 406(29), 7633–7640. https://doi.org/10.1007/s00216-014-8213-x

Mor-Mur, M., & Yuste, J. (2009). Emerging Bacterial Pathogens in Meat and Poultry: An Overview. Food and Bioprocess Technology, 3(1), 24. https://doi.org/10.1007/s11947-009-0189-8

Muñoz-Zanzi, C., Mason, M. R., Encina, C., Astroza, A., & Romero, A. (2014). Leptospira Contamination in Household and Environmental Water in Rural Communities in Southern Chile. International Journal of Environmental Research and Public Health, 11(7), 6666–6680. https://doi.org/10.3390/ijerph110706666

Pests. (n.d.). Retrieved October 18, 2019, from http://www.foodstandards.gov.au/foodsafety/standards/Pages/Pests.aspx

Rasheed, M. U., Thajuddin, N., Ahamed, P., Teklemariam, Z., & Jamil, K. (2014). ANTIMICROBIAL DRUG RESISTANCE IN STRAINS OF Escherichia coli ISOLATED FROM FOOD SOURCES. Revista Do Instituto de Medicina Tropical de São Paulo, 56(4), 341–346. https://doi.org/10.1590/S0036-46652014000400012

Samiullah, Chousalkar, K. K., Roberts, J. R., Sexton, M., May, D., & Kiermeier, A. (2013). Effects of egg shell quality and washing on Salmonella Infantis penetration. International Journal of Food Microbiology, 165(2), 77–83. https://doi.org/10.1016/j.ijfoodmicro.2013.05.002

SARTZ, L., De JONG, B., HJERTQVIST, M., PLYM-FORSHELL, L., ALSTERLUND, R., LÖFDAHL, S., … KARPMAN, D. (2008). An outbreak of Escherichia coli O157:H7 infection in southern Sweden associated with consumption of fermented sausage; aspects of sausage production that increase the risk of contamination. Epidemiology and Infection, 136(3), 370–380. https://doi.org/10.1017/S0950268807008473

Shell Eggs from Farm to Table. (n.d.). Retrieved October 18, 2019, from https://www.fsis.usda.gov/wps/portal/fsis/topics/food-safety-education/get-answers/food-safety-fact-sheets/egg-products-preparation/shell-eggs-from-farm-to-table/CT_Index

Smith, D. P., Berrang, M. E., Feldner, P. W., Phillips, R. W., & Meinersmann, R. J. (2004). Detection of Bacillus cereus on selected retail chicken products. Journal of Food Protection, 67(8), 1770–1773. https://doi.org/10.4315/0362-028x-67.8.1770

Soares, C. M., Kabuki, D. Y., & Kuaye, A. Y. (2012). Growth of enterotoxin producing Bacillus cereus in meat substrate at 10^oC and 30^oC. Brazilian Journal of Microbiology: [Publication of the Brazilian Society for Microbiology], 43(4), 1401–1405. https://doi.org/10.1590/S1517-838220120004000022

Soni, A., Oey, I., Silcock, P., & Bremer, P. (2016). Bacillus Spores in the Food Industry: A Review on Resistance and Response to Novel Inactivation Technologies. Comprehensive Reviews in Food Science and Food Safety, 15(6), 1139–1148. https://doi.org/10.1111/1541-4337.12231

T.C. Forensic: Article 10—PHYSICAL CONSTANTS FOR INVESTIGATORS. (n.d.). Retrieved October 11, 2019, from http://www.tcforensic.com.au/docs/article10.html

Tewari, A., Singh, S. P., & Singh, R. (2015). Incidence and enterotoxigenic profile of Bacillus cereus in meat and meat products of Uttarakhand, India. Journal of Food Science and Technology, 52(3), 1796–1801. https://doi.org/10.1007/s13197-013-1162-0

Tyler, C. (1945). The porosity of egg shells, and the influence of different levels of dietary calcium upon porosity. The Journal of Agricultural Science, 35(3), 168–176. https://doi.org/10.1017/S0021859600049182

V. T. Nair, D., Venkitanarayanan, K., & Kollanoor Johny, A. (2018). Antibiotic-Resistant Salmonella in the Food Supply and the Potential Role of Antibiotic Alternatives for Control. Foods, 7(10). https://doi.org/10.3390/foods7100167

Vadehra, D. V., Baker, R. C., & Naylor, H. B. (1970). Role of Cuticle in Spoilage of Chicken Eggs. Journal of Food Science, 35(1), 5–6. https://doi.org/10.1111/j.1365-2621.1970.tb12354.x

Välsänen, O. M., Mentu, J., & Salkinoja‐Salonen, M. S. (1991). Bacteria in food packaging paper and board. Journal of Applied Bacteriology, 71(2), 130–133. https://doi.org/10.1111/j.1365-2672.1991.tb02967.x

Water Treatability Database. (n.d.). Retrieved October 27, 2019, from https://iaspub.epa.gov/tdb/pages/contaminant/contaminantOverview.do?contaminantId=10100

Zhang, X., Li, Y., Liu, B., Wang, J., Feng, C., Gao, M., & Wang, L. (2014). Prevalence of Veterinary Antibiotics and Antibiotic-Resistant Escherichia coli in the Surface Water of a Livestock Production Region in Northern China. PLoS ONE, 9(11). https://doi.org/10.1371/journal.pone.0111026