Nothing's Virgin Here

Belgian researchers improve the taste of beer.

A study recently published in Applied and Environmental Microbiology shows development of modern beer with enhanced taste by identifying and genetically modifying a gene that contributes significantly to the flavor of beer and several other alcoholic beverages.

For many years, beer was brewed in open, horizontal vats. However, the industry transitioned to using large, closed vessels in the 1970s because they are simpler to fill, empty, and clean, allowing brewing in greater volumes while also incurring lower expenses. However, because of insufficient flavor production, these modern techniques produced lower-quality beer.

During fermentation, yeast transforms half of the sugar in the mash into ethanol and half into carbon dioxide. The issue is that the carbon dioxide pressurizes these tight containers, reducing flavor.

Johan Thevelein, Ph.D., an emeritus professor of Molecular Cell Biology at Katholieke Universiteit, and his group had previously developed technology for identifying the genes in yeast responsible for commercially important traits. They used this technology to find the gene(s) responsible for flavor in beer by screening a large number of yeast strains to see which performed the best job of retaining flavor under pressure.

Thevelein (founder of NovelYeast) said they concentrated on a gene for a banana-like flavor since it is “one of the most important flavors present in beer, as well as in other alcoholic drinks.”

“To our surprise, we identified a single mutation in the MDS3 gene, which codes for a regulator apparently involved in the production of isoamyl acetate, the source of the banana-like flavor that was responsible for most of the pressure tolerance in this specific yeast strain.”

Said Thevelein

Thevelein and coworkers then used CRISPR/Cas9, a revolutionary gene editing technology, to engineer this mutation in other brewing strains, which similarly improved their tolerance of carbon dioxide pressure, enabling full flavor. “That demonstrated the scientific relevance of our findings, and their commercial potential,” said Thevelein.

“The mutation is the first insight into understanding the mechanism by which high carbon dioxide pressure may compromise beer flavor production,” said Thevelein, who noted that the MDS3 protein is likely a component of an important regulatory pathway that may play a role in carbon dioxide inhibition of banana flavor production, adding, “how it does that is not clear.”

The technology has also been successful in identifying genetic elements important for rose flavor production by yeast in alcoholic drinks, as well as other commercially important traits, such as glycerol production and thermotolerance.

The researchers believe that their method will also be effective in discovering genetic factors necessary for the generation of rose flavor by yeast in alcoholic beverages.

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