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Genetic Diversity Of Beer Yeasts Leaves Wine In Shade

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Stephen Luntz

Stephen has a science degree with a major in physics, an arts degree with majors in English Literature and History and Philosophy of Science and a Graduate Diploma in Science Communication.

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beer testing

Dr José Paulo Sampaio and colleagues had a lot of fun researching the genetics of yeasts for making beer. Joseph Caputo

Here's something beer drinkers might find useful the next time they're being patronized by wine snobs: The yeasts that make beer are actually far more genetically diverse than those used for wine. Consequently, it might be argued, beer is actually the more complex and sophisticated drink.

Dr José Paulo Sampaio of the Universidade Nova de Lisboa sampled 90 yeasts from around the world and studied their relationships to each other. He found three broad groups of beer yeasts: German, British, and wheat beers, with a considerable diversity within these groups. Moreover, some beer yeasts are so different from these three that they are more closely related to those used for bread, sake, or wine than to the mainstream microorgranisms used to make the amber fluid.

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“We were surprised to find that the genetic diversity of beer yeasts was much higher than that of wine yeasts,” Sampaio said in a statement. “We were even more surprised to learn that, besides forming a new group that we call the Beer clade, beer yeasts form additional groups. Whereas wine yeasts from any place in the world, say France and New Zealand, cluster in the same group and are genetically very similar, quite the opposite is true for beer yeasts.”

In Current Biology, Sampaio proposes that yeast genetics provide an indication of the timing of yeast domestication, with most beers descending from an event that probably occurred 5,000 to 6,000 years ago in the Fertile Crescent, although a beer-like drink was made from fruit and rice in China 9,000 years ago. The genetic resemblance of a minority of beer yeasts to those used for other foods, on the other hand, probably reflects the fact that in more recent times, yeasts used for other foods were repurposed to make beer, capturing niches in beer production.

Beer yeasts are classified as two separate species. Saccharomyces cerevisiae makes both bread and “top-fermenting” ales formed in warm conditions. Saccharomyces pastorianus, on the other hand, produces “bottom-fermenting” lagers. Despite this division, Sampaio's work indicates that genetically S. pastorianus is a relatively homogenous subgroup within the diversity of the main group of beer yeasts, albeit a subgroup that has captured 94 percent of the commercial beer market.

S pastorianus' lack of diversity reflects the fact that lager brewing originated in the 15th century, thousands of years after ales, and only came to popular domination in the 19th century.

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Despite focusing on beer yeasts, Sampaio's comparison of domesticated yeast strains with wild varieties reveals that wine yeasts came from strains associated with oak trees.

If wine drinkers disagree that the genetics of yeast are the important test as to the sophistication of alcohol forms, beer-lovers might hypothesize that oenologists are just incapable of detecting the true subtlety of flavors beer yeasts' extraordinary genetic diversity makes possible.

 


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