Tweaking Banana Flavor Gene Can Improve Beers' Taste, Study Finds

Microbiologists have cracked the code for a more flavorful beer. Interestingly, modifying a single gene responsible for a fruity banana flavor seems to increase beer quality with improved taste.

First, one needs to understand what causes modern beers to have inferior quality.

In earlier times, beer was brewed in open horizontal vats. But with time, the process was shifted to large, closed vessels. This new method made the filling, emptying, and cleaning of the vessels a lot easier, while boosting production scale and bringing down the costs.

However, when fermentation takes place in these closed vessels, yeast converts 50 percent of the sugar in the mash to ethanol and the remaining 50 percent to carbon dioxide, which is the natural process. But the carbon dioxide gets trapped in the closed vessels and exerts pressure on the vessel, leading to insufficient flavor production.

In the study, published in the journal Applied and Environmental Microbiology, researchers screened a large number of yeast strains to find the gene(s) which help in retaining the most flavor to the beer under pressure.

After research, scientists narrowed it down to one particular gene called MDS3, which is responsible for giving the beer a banana-like flavor. The spotlight was on the banana flavor gene "because it is one of the most important flavors present in beer, as well as in other alcoholic drinks," lead author Johan Thevelein, an emeritus professor of Molecular Cell Biology at Katholieke Universiteit, said.

"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," Thevelein added

With the help of CRISPR/Cas9, a gene-editing technology, researchers introduced this mutation to other brewing strains. The result was an improved tolerance of pressure from carbon dioxide, which helped realize enhanced flavor.

"That demonstrated the scientific relevance of our findings, and their commercial potential," Thevelein commented.

Thevelein noted that the gene MDS3 is most probably part of a regulatory pathway that inhibits banana flavor production due to carbon dioxide, but "how it does that is not clear."

Yet, signifying the findings of the study, Thevelein added, "The mutation is the first insight into understanding the mechanism by which high carbon dioxide pressure may compromise beer flavor production."

The same technology, called polygenic analysis, has also been used to identify other flavor-enhancing genetic elements that favor the production of compounds like phenyl ethyl acetate which gives rose and honey flavors, and ethyl esters that provide apple-like flavor to beer and other alcoholic drinks.