The Genetics of Beer

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As a beer, Guinness stands out for its flavor and color, but a new study is showing that it’s also genetically distinct: Scientists have discovered that the yeast strains used to produce the world’s most famous stout are different from those used to make other Irish beers, New Scientist reported.

Brewer’s yeast – scientifically known as Saccharomyces cerevisiae – is an important element in beer-making: The microorganisms help convert sugars from malt into alcohol and carbon dioxide during the fermentation process.

Different yeast strains can produce different types of brews, such as stouts or lagers, as well as influence flavor.

Researcher Daniel Kerruish and his team looked into Guinness’ historical records, including the types of yeasts used to brew the stout over the years since 1903.

They took the genomes of 13 strains of S. cerevisiae that are currently used and have been used in the past to brew Guinness and compared them with 160 other strains.

The findings showed that while the yeasts used by Guinness and other Irish brewers belonged to the same lineage, the stout’s strain belonged to a previously unidentified subpopulation.

These unique strains produced a peculiar balance of flavor compounds, such as 4-vinyl guaiacol and diacetyl – which respectively give a clove-like aroma and a buttery taste.

And two of these strains currently used by the Irish brewer are descendants of one used more than a century ago.

“The more we learn about the Guinness yeast the more we realize how unique and special it is,” said Kerruish. “Perhaps we shouldn’t be surprised since Guinness is an amazing beer.”