Secret of lager beer discovered in Argentina

Scientists have finally traced the ancestry of German lager — all the way back to Argentina.

The Saccharomyces eubayanus species of yeast arrived by chance in 15th-century Europe, transported across the Atlantic from Argentina's Patagonia region.

The stowaway yeast could have traveled on a piece of wood or in the stomach of a fruit fly. Once it arrived, it fused with a distant relative used at the time to make ale.

Until the late 15th century, ales were brewed at about 77 degrees Fahrenheit, and served at no less than 54 degrees Fahrenheit, because the yeast used for fermentation could not withstand cold temperatures.

The arrival of the hybrid yeast, which thrives in cooler climates, was key to the invention of the German lager, which is created from malted barley and brewed at low temperatures.

For years, scientists have been searching for the unidentified yeast that helped give rise to the lager, now one of the most popular types of beer worldwide.

Finally a team of researchers discovered the yeast on beech trees in Patagonia. They then sequenced the yeast's genome and concluded that they had found the missing link in the evolution of lager. Their findings are reported in the Proceedings of the National Academy of Sciences.

The discovery, scientists say, could help them pinpoint the effects of domestication in the genome of brewing yeasts. More interestingly, it could also help brew better beers.

Follow Stephanie on Twitter: @stephaniegarlow

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