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Yeast Hunting at Historic Caucasus Mountain Brewing Sites

Shanleigh Thomson

Ancient Yeasts May Unlock New Possibilities in Brewing

Summary:

  1. An international team of experts, led by researchers from the Technical University of Munich and Georgian Technical University, investigates the history of brewing yeast in ancient Georgian sites.

  2. The search focuses on discovering cold-tolerant yeast strains in the diverse microflora of Georgia's Caucasus mountains, aiming to uncover the origins of lager yeast.

  3. The findings from this study could greatly impact our understanding of brewing processes, enhance yeast biology knowledge, and influence the brewing industry's innovation.


A team of archaeologists and brewing experts has launched an investigation into historic brewing sites in the Caucasus mountains of Georgia, searching for unique, special brewing yeasts. Led by Mathias Hutzler and Martin Zarnkow of the Technical University of Munich (TUM), alongside Lia Amiranashvili and Giorgi Kvartskhava from the Georgian Technical University, and Juan Eizaguirre from the Universidad Nacional del Comahue in Argentina, the research effort is combining traditional yeast hunting with a historical context.

Yeast is essential to beer brewing, and a cold-tolerant variety known as 'bottom-fermenting yeast' has played a key role in the global success of lager. Despite years of research, the exact "parents" of this yeast have not yet been identified. This joint research team hopes to crack that mystery.

Given that hops - a key ingredient in most beers - originally came to Central Europe from Georgia, the researchers theorized that the origins of the bottom-fermenting yeast might also lie in Georgia. The diverse microflora in Georgia, especially in the high mountain regions, offers a unique environment that may house the ancestors of this valuable yeast strain.

The team's expedition covered different sites in Georgia, analyzing the region's microbial biodiversity, and conducting anthropological studies on brewing in the Caucasus's high mountain region. Their search focused on yeast strains that are both cold-tolerant and thrive in beer wort, a sugary liquid critical to the brewing process.

The journey took the team through ancient forests rich in biodiversity and traditional mountain breweries. Along the way, they sampled regional beers, noted their unique brewing processes, and gained insights into the traditional brewing customs.

The team also collected around 200 samples, including substrates like soil, bark, leaves, fruits, fungi, and samples related to the brewing process. Moreover, they discovered that hops grow wild in the region, even at altitudes up to 1800 meters.

One intriguing insight from interviews with local brewers pointed towards the potential role of the brewer's microbiome in the brewing process. Customs such as a month-long purification ritual in the forest, followed by the brewing process, may influence the brewing process and the yeast involved.

These findings from the Caucasus will significantly contribute to understanding how brewing processes have evolved. While Georgia is known today for its wines, fermented in large clay amphorae called qvevris, these researchers believe that Georgia may also be home to a wide variety of brewing yeasts.

The origin of lager yeast is a fascinating story that goes back to the 17th century. The yeast used to brew most modern lagers, known as Saccharomyces pastorianus, came into existence due to a serendipitous blending of yeasts from a white ale and a brown beer in a Munich brewery cellar, between the years 1602 and 1615 (Khasmi, 2022). At that time, brewers didn't know about the existence of yeast but they realized that this new blend provided a unique advantage—it fermented like an ale, yet it could also withstand colder temperatures akin to a brown beer. This meant that a clean-tasting lager could be brewed earlier in the spring in the Northern Hemisphere, which was especially important during the cold years of the Little Ice Age (1300 to 1850 C.E.) (Khasmi, 2022).

Saccharomyces pastorianus is a hybrid species, created from the union of the top-fermenting ale yeast Saccharomyces cerevisiae and the cold-tolerant Saccharomyces eubayanus (Krogerus, 2022a). This advantageous blending of yeasts occurred when S. cerevisiae was introduced into an environment where S. eubayanus was already present (Krogerus, 2022a)

Today, Saccharomyces pastorianus is responsible for brewing lager-style beers which account for 90% of all beer sold globally (Khasmi, 2022), amounting to the production of almost 200 billion liters of lager-type beer annually (Gibson, 2019).

The work being done by researchers in Georgia is of great importance due to a couple of reasons. One, it furthers our understanding of yeast biology and the processes involved in beer brewing. This knowledge can potentially lead to the development of new yeast strains or brewing techniques, which can then produce new types of beer with distinct tastes and aromas.

Second, yeast is not only important for brewing beer, but it also has broad significance in biotechnology. Understanding the genetic and evolutionary history of yeasts like Saccharomyces pastorianus can help us harness these organisms for a wide range of applications, from biofuel production to pharmaceuticals.

Lastly, with the brewing industry facing increasing demand for innovative products, research into yeasts and brewing processes can lead to the creation of distinctive and unusual products that could satisfy this demand (Krogerus, 2022b). By understanding the origins of lager yeast and how it functions, we can enhance our ability to innovate within this industry, ultimately creating new products that can cater to a wide range of consumer tastes and preferences.

The potential discovery of the 'parent' yeast strains to lager could open new possibilities for the brewing industry. The 'yeast hunt' conducted by this dedicated team exemplifies how scientific curiosity and innovative research can shed light on the past to create a more flavorful future.

References

  1. Khamsi, R. (2022, April 18). "Modern lager arose when a beer and an ale met in a Munich brewhouse". Science.org. Retrieved July 27, 2023, from https://www.science.org/content/article/modern-lager-arose-when-beer-and-ale-met-munich-brewhouse

  2. Krogerus, K., Magalhães, F., Vidgren, V., & Gibson, B. (2022). "A new hypothesis for the origin of the lager yeast Saccharomyces pastorianus". PubMed. Retrieved July 27, 2023, from https://pubmed.ncbi.nlm.nih.gov/37102188/

  3. Gibson, B., Geertman, J. A., Hittinger, C. T., Krogerus, K., Libkind, D., & Louis, E. J. (2019). "Lager-brewing yeasts in the era of modern genetics". Fems Yeast Research, 19(7). Academic.oup.com. Retrieved July 27, 2023, from https://academic.oup.com/femsyr/article/19/7/foz063/5573808

  4. Krogerus, K., Holmström, S., Gibson, B. (2022). "Beyond Saccharomyces pastorianus for modern lager brews: Exploring non-cerevisiae Saccharomyces hybrids with heterotic maltotriose consumption and novel aroma profile". Frontiers in Microbiology. Frontiersin.org. Retrieved July 27, 2023, from https://www.frontiersin.org/articles/10.3389/fmicb.2022.1025132/full

  5. Gibson, B., Geertman, J. A., Hittinger, C. T., Krogerus, K., Libkind, D., Louis, E. J. (2019). "Lager brewing yeasts in the era of modern genetics" (PDF). Researchgate.net. Retrieved July 27, 2023, from https://www.researchgate.net/publication/336039546_Lager_brewing_yeasts_in_the_era_of_modern_genetics

  6. Charpentier, C., Feuillat, M., Maujean, A. (2023). "Impact of the genetic improvement of fermenting yeasts on the organoleptic properties of beer". Food Science and Technology International. Springer.com. Retrieved July 27, 2023, from https://link.springer.com/article/10.1007/s00217-023-04251-8

  7. Bellut, K., Michel, M., Zarnkow, M., Hutzler, M., Jacob, F., De Schutter, D. P., Daenen, L., Lynch, K. M., Zannini, E., Arendt, E. K. (2018). "Conventional and Non-Conventional Yeasts in Beer Production". Fermentation, 4(2). Mdpi.com. Retrieved July 27, 2023, from https://www.mdpi.com/2311-5637/4/2/38

  8. Gibson, B., & Krogerus, K. (2022, February 17). "How we discovered the true origins of a pint of lager – new research". Theconversation.com. Retrieved July 27, 2023, from https://theconversation.com/how-we-discovered-the-true-origins-of-a-pint-of-lager-new-research-202573

  9. Hutzler, M., Amiranashvili, L., Eizaguirre, J., Kvartskhava, G., & Zarnkow, M. (2023, February 15). "Yeast hunting at historic Caucasus Mountain brewing sites: Investigations for special brewing yeasts in Georgia". The European Archeologist, 75. European Association of Archaeologists. Retrieved July 27, 2023, from [https://www.e-a-a.org/EAA/Publications/Tea/Tea_75/Ongoing_research/EAA/Navigation_Publications/Tea_75_content/Ongoing_research.aspx].