So, back in 2011 I mentioned the discovery of S. eubayanus in the wild in Patagonia. That’s exciting because S. pastorianus (often called “lager yeast” in English: it’s the yeast used to make a lot what the world recognizes as “beer” today, for better or worse) is actually a hybrid of two other kinds of yeast: that is, it was formed when two different kinds of yeast contributed DNA to a hybrid yeast. Those two yeasts were S. cerevisae (familiar as top-fermenting brewer’s yeast, but in fermenting other alcohols and making bread as well), and an until-recently mysterious, never-before isolated strain that got called S. eubayanus. The latter yeast was the one that contributed the metabolic properties that allow it to function in colder temperatures, and add to the complications involved in the brewing process, including the “lagering” stage for which the beer style is called.1
What’s weird was that until 2011, S. eubayanus had never yet been found in the wild. When you compare that to S. cerevisae, it’s odd: S. cerevisae is everywhere—even on your skin, in the air in your home, on the skins of fruit, and so on. So when S. eubayanus was found in the Patagonian rainforest, it caused quite an uproar in the beer world. That said, people did wonder how in the hell S. eubayanus could have gotten from Patagonian forests all the way to Bavaria.
Well, since then—back in 2014—it seems researchers found strains of S. eubayanus in Asia—specifically on the Tibetan plateau (like Patagonia, a high-elevation, chilly place) and they’re claiming genetic analysis shows a closer relation to the archaic strain of S. eubyanaus that would have contributed to the S. pastorianus genome. (Here’s a link to the PDF for the paper reporting the find.)
That means Europeans may have gotten lager yeast not from South America, but via the Silk Road… maybe. Who knows whether some strain of S. eubayanus will get found somewhere further West sometime soon? Anything’s possible, it seems… which makes for exciting times, whether you’re a beer-history nut or a beer science geek, or even just an interested onlooker.
What’s strange is how little press the second find got. Everyone was excited about the Patagonia find; the one in Tibet, not so much. Or maybe I just missed it, I don’t know. In any case, this was excuse enough to update my essay “Imaginary Beers & Boozes: A Primer for the SFF Writer.”
“Lagering” is a period of extended cold storage necessary for beers fermented with S. pastorianus; it allows the yeast to finish its fermentation and metabolize byproducts of fermentation; with top-fermenting yeasts working warmer temperatures, this stage isn’t necessary, but the characteristics of those yeasts are more noticeable in the final product, where “lagers” feature less yeast character and, I’d say, more transparently feature the character of the malts and hops used.)↩