Cold Lager Beer a Result of Accidental Yeast Journey, Study Says

Aug. 22 (Bloomberg) -- Scientists say they’ve found the missing link. For beer, not humans.

The yeast that’s the biological difference between ale, brewed at room temperatures, and cold-brewed lager that can be stored for longer periods and still retain its taste, isn’t native to Bavaria, where lager was first made by monks in the 15th century. It comes from South America, researchers say.

Now that the yeast’s genomic foundation is identified, researchers say it could be manipulated to create new types of designer beers. The microbe was found to exist on beech trees in Patagonia, and may have made the 7,000-mile trip to Bavaria in wood, or in the guts of mice or flies, the researchers reported today in the Proceedings of the National Academy of Sciences.

Because of the find, “you could envision an age of designer yeast strains where brewers can pick the kind of genetic traits you like,” said Chris Hittinger, an assistant professor at the University of Wisconsin-Madison and a study author.

The yeast eluded the researchers for five years until one of the team, Diego Libkind, discovered the strain, Saccharomyces eubayanus, in fungi growing off the beech trees in Argentina. He has signed an agreement with a microbrewery near Bariloche, Argentina, to develop new beverages using the yeast.

“We’re working together in the diversification of their products using eubayanus or artificially forced eubayanus hybrids,” Libkind, a researcher at the Bariloche-based Institute for Biodiversity and Environment Research, said in an e-mail.

Sugar Ingredient

The yeast strain is produced by the trees during a bacterial infection in which a fungus attacks the beech and the tree produces a growth called a gall, a mixture containing the yeast, plant cells, fungi, and the key ingredient -- sugar, said Hittinger.

“Those galls are very sugar-rich and ferment the tree. You can smell it in the forest,” Hittinger said. “Local people in this area would chop these galls off and eat them in salads.”

Cooler Patagonian temperatures mean that the yeast adapted to ferment in a cold environment, he said, giving it the refrigerated brewing capability that gives lagers their chilled nature.

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