Researchers in Belgium have enhanced the flavor of modern beer by locating and genetically modifying a gene that contributes significantly to the flavor of beer and some other alcoholic beverages. The study has been published in the American Society for Microbiology journal, Applied and Environmental Microbiology.
Beer was traditionally produced in open, horizontal vats. However, the industry switched to using large, closed vessels in the 1970s because they are much simpler to fill, empty, and clean, allowing for higher production rates and lower costs. However, due to insufficient flavor production, these contemporary methods produce beer of lower quality.
In the course of fermentation, yeast turns half of the mash’s sugar into ethanol and the other half into carbon dioxide. The issue is that the pressure of the carbon dioxide inside these sealed containers mutes flavor.
At Katholieke Universiteit, Johan Thevelein, Ph.D., an emeritus professor of Molecular Cell Biology, and his group had invented a technique for identifying the genes in yeast that were in charge of important traits for industry. By analyzing a large number of yeast strains to determine which did the best job of maintaining flavor under pressure, they used this technology to identify the gene(s) responsible for the flavor in beer. Thevelein, who founded NovelYeast and works with other businesses in industrial biotechnology, said they concentrated on a gene for a banana-like flavor because it is “one of the most important flavors present in beer, as well as in other alcoholic drinks.”
To our surprise, we found a single mutation in the MDS3 gene. This gene codes for a regulator that seems to be involved in the production of isoamyl acetate, which gives the banana-like flavor and was responsible for most of the yeast strain’s pressure tolerance, said Thevelein.
Thevelein and colleagues next engineered this mutation in additional brewing strains using the cutting-edge gene editing technique CRISPR/Cas9, which also increased the strains’ tolerance to carbon dioxide pressure and enabled full flavor. Thevelein said, “That showed how important our findings were to science and how they could be used in business.”
Thevelein 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 that “how it does that is not clear.” He also said that the mutation is the first clue to how high carbon dioxide pressure might affect the flavor of beer.
Also, the technology has helped find the genetic parts that yeast needs to make the rose flavor in alcoholic drinks, as well as other traits that are important for business, like making glycerol and being able to handle high temperatures.
