Contains GMOs!
Belgian scientists used genetic engineering to improve the taste of beer
Nikita Loginov, Naked Science
Biologists of the Catholic University of Leuven (Belgium) have created a "genetic patch" for brewer's yeast, which allows you to brew beer at high pressure without losing the richness of taste. After genome editing using CRISPR/Cas9 technology, yeast, when cooked under excessive pressure, produced an average of 145% more aromatic esters, scientists report in the journal Applied and Environmental Microbiology (Souffriau et al., Polygenic Analysis of Tolerance to Carbon Dioxide Inhibition of Isoamyl Acetate “Banana” Flavor Production in Yeast Reveals MDS3 as Major Causative Gene).
Historically, beer was brewed in open horizontal containers, but with the increase in consumption of the foam drink, brewers switched to large closed vessels. They are easier to fill, empty and clean, besides, sealed sealed containers do not allow germs and contaminants to get into the beer and spoil it. Yeast does not like foreign impurities in the fermentation process very much.
However, large closed vessels are also not ideal for brewing beer. Pressure is constantly increasing in such vessels, which affects fermentation and worsens the taste of the drink. Excessive pressure reduces the production of isoamyl acetate, an ester that creates a feeling of banana (or pear) smell and taste. Oddly enough, it is this fruit component that makes the cumulative taste of beer so characteristic and rich. And it is very sensitive to pressure: after 0.5 bar (half atmospheric pressure), isoamyl acetate production drops exponentially, and at 2.7 bar it stops completely.
In large industrial tanks, the liquid alone creates a hydrostatic pressure reaching up to 1.8 bar. Yeast itself, during fermentation, releases not only alcohol, but also carbon dioxide, which increases the pressure. This gas is deeply dissolved in the liquid and it will not be removed quickly. In general, it is hardly possible to completely get rid of the increase in pressure when brewing beer. Yes, it is not necessary, because excessive pressure can be useful: for example, it suppresses the formation of fusel alcohols and acetate esters, which has a good effect on the quality of beer. Therefore, it makes sense to make the beer taste resistant to high pressure during cooking.
Scientists have tried to find out which genes of brewer's yeast are responsible for the production of isoamyl acetate during fermentation. It turned out that the production of "fruit flavor" can be regulated by a single "switch" - a mutation in the MDS3 gene. Using CRISPR/Cas9 technology, biologists edited the genome of 423 strains of Saccharomyces cerevisiae brewing yeast, giving them the ability to actively produce isoamyl acetate under excessive pressure.
Diagram of a laboratory apparatus for brewing beer from Belgian scientists / © Catholic University of Leuven.
To check the result, biologists used a homemade brewing apparatus, similar in characteristics to large industrial installations for brewing beer. As expected, genetically modified yeast has become less sensitive to CO2 pressure. Even at 1.65-1.8 bar, isoamyl acetate production decreased minimally, and on average its production at overpressure increased by 145% relative to conventional yeast. The researchers are confident that their method will interest brewers and quickly conquer the market, because it allows you to produce huge volumes of beer with a deep and rich taste.
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