Lager yeast is actually a different species of yeast than Saccharomyces cerevisiae, which earned it the different name. This is opposed to the various strains of Saccharomyces cerevisiae, which include the various ale strains and even baker's yeast. While the strains behave differently in the brew house and produce different flavors and aromas, they are basically the same yeast. Lager yeast is different all together and the differences allow it to endure and out-compete other yeasts in cooler temperatures.
However, scientists were unable to fully map lager yeast's genetic parents. They knew that one precursor was Saccharomyces cerevisiae itself, but the other main precursor was unknown, until now. An international team of researchers discovered a yeast that lives in galls that infect beech trees in the forests of Patagonia. The yeast, which researchers named Saccharomyces eubayanus, is a 99.5% genetic match for the missing precursor to lager yeast. "Beech galls are very rich in simple sugars. It's a sugar rich habitat that yeast seem to love" says Chris Todd Hittinger, a co-author of the study. Combine a sugar rich environment with cold temperatures, such as the -2 degree C average daily lows in the Patagonia beech tree forests, and you have the perfect parent to lager yeast.
How the Saccharomyces eubayanus got from Patagonia to Bavaria remains a mystery.
Cheers,
TW
No comments:
Post a Comment