Celebrating microbes on this National Beer Day!

National Beer Day is special for Shiru because we tend to get excited about all things fermentation. Fermentation is how we produce our protein ingredients and it’s how brewers make beer. Our ingredient discovery platform, Flourish™, utilizes computational methods and precision fermentation to identify and create the next-generation of plant-based functional food proteins [1]. While precision fermentation is a relatively new technology, the core concept is similar to traditional fermentation. Both types of fermentation harness the power of microbes to transform nutrients into a tasty (or tasteless, but highly functional) final product. My colleagues have written posts that detail how we use  precision fermentation to make recombinant proteins. In this post I will take a diversion into the world of traditionally fermented beverages.

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The history of fermented beverages extends back millenia.  Archeologists have performed trace chemical analysis on residues from vessels unearthed in Iran, China, and Israel to reveal the presence of fermented beverages. Figure 1 highlights three research articles that document these discoveries, with the oldest example dating back to 13,700 - 11,700 B.C. [2, 3, 4] 

Early fermented beverages were quite different from modern beer. Most modern beer styles are composed of four ingredients: 1) water, 2) hops to add bitterness and aroma, 3) malted barley to add flavor and sugar, and 4) yeast, the magical microbes that transform these ingredients into beer. During fermentation, yeast convert sugar into ethanol and carbon dioxide as they grow [5]. Ancient brews utilized various sugar sources such as barley, rice, fruit, honey, wheat, oats, and flaxseed and relied on naturally occurring microbes for fermentation [2, 3, 4]. How different are ancient brews from modern beer? Curious individuals can taste recreations of ancient beverages such as Ancient Ales, a collaboration between brewers at Dogfish Head Brewery and molecular archeologist Dr. Patrick McGovern

At Shiru, we appreciate the microbes that produce our protein ingredients and beer exemplifies the uniqueness of these microbes. Beyond their role in converting sugar to ethanol, yeast and other microbes play a key role in flavoring different beer styles. Brewers ale yeast Saccharomyces cerevisiae produce flavor-active molecules such as fusel alcohols, esters, fatty and organic acids during fermentation [6]. S. cerevisiae strains contribute  to the distinct flavor and aroma profiles in ales such as belgian saisons, hefeweizens, and IPAs. Creating reproducible flavor profiles of each beer style requires careful management of yeast stocks and fermentation conditions in the brewery to avoid contamination by bacteria or wild yeast. However, some beer styles owe their unique flavors to controlled introduction of these microbes. The bacteria Lactobacillus creates lactic acid present in many sour beers while the wild yeast Brettanomyces produce fruity aromas and barnyard, horsey aromas that are desirable in certain styles. One particularly interesting brew is the Beard Beer by Rogue, which is brewed with wild yeast harvested from the beard of their brewer, John Maier.

While ingredient and microbe selection impacts flavor, this is not the only strategy for creating a flavor profile. At the nexus between precision fermentation in biotechnology and classic brewing, scientists at Berkeley Yeast have engineered brewing yeast to produce the aromatic terpenes naturally present in hops to add to the flavor profile, enabling big aromatic hop profiles with reduced hop usage.

In the words of Franklin Roosevelt, “I think this would be a good time for beer.” I will be celebrating microbes and fermentation by visiting my favorite local brewery, Laughing Monk.  If you are in the Bay Area, you can check out this list to find a local brewery near you.

References:

1. The Good Food Institute. State of the Industry Report - Fermentation: An Introduction to a Pillar of the Alternative Protein Industry 2020 https://gfi.org/resource/fermentation-state-of-the-industry-report/
2. Rudolph H. Michel, Patrick E. McGovern, and Virginia R. Badler “The first wine & beer. Chemical detection of ancient fermented beverages” Analytical Chemistry 1993 65 (8) 408A-413A. DOI: 10.1021/ac00056a002
3. Patrick E. McGovern, Juzhong Zhang, Jigen Tang, Zhiqing Zhang, Gretchen R. Hall, Robert A. Moreau, Alberto Nuñez, Eric D. Butrym, Michael P. Richards, Chen-shan Wang, Guangsheng Cheng, Zhijun Zhao, and Changsui Wang "Fermented beverages of pre- and proto-historic china", Proc. Nat. Acad. Sci 2004 101(51) 17593-17598. DOI: 10.1073/pnas.0407921102
4. Li Liu, Jiajing Wang, Danny Rosenberg, Hao Zhao, Gyorgy Lengyel, and Dani Nadel “Fermented beverage and food storage in 13,000 y-old stone mortars at Raqefet Cave, Israel: Investigating Natufian ritual feasting” Journal of Archeological Science: Reports 2018 (21) 783-793. DOI: 10.1016/j.jasrep.2018.08.008
5. Bamforth, C.W. Scientific Principles of Malting and Brewing. 2006 Scientific Society of Brewing Chemists
6. Ademola O. Olaniran, Lettisha Hiralal, Mduduzi P. Mokoena, and Balakrisna Pillay “Flavour-active volatile compounds in beer: production, regulation and control” 2017 Journal of the Institute of Brewing. DOI: 10.1002/jib.389