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DateDate: 10-12-2019, 05:47

Researchers have reported in the ACS Journal of Agricultural and Food Chemistry that they have bred yeast for lager, which will extend the shelf life of the beer and lead to improved taste stability, writes FaceNews.ua.
As it turned out, the stale aroma and taste of beer is associated with aldehyde compounds of the type (E) -2-nonenal and acetaldehyde, which are formed by yeast during fermentation and during chemical reactions during storage of the lager.
Brewers used various methods to reduce the level of such compounds in the composition of the beverage by controlling the fermentation conditions or adding antioxidants. However, this did not have a significant effect - beer still deteriorates relatively quickly.
 
Therefore, a group of scientists led by Qi Li genetically modified camp yeast, which could produce more NADH molecules (reduced nicotinamide adenine dinucleotide).
They, in turn, increase the activity of natural yeast enzymes that can change aldehydes to other types of compounds that affect the taste and shelf life of beer.
During the experiment, the genetic technique of “overexpression” was used, thanks to which the expression level of various genes associated with the synthesis of NADH was artificially increased.
By trial and error, 4 genes were identified, with overexpression of which the number of produced NADH molecules increased. With the further use of modified yeast in brewing, the acetaldehyde content in the camp was 26.3–47.3% less than in the control samples.
In addition, the new strain produced more sulfur dioxide, a natural antioxidant that also prevents the aging of beer. The remaining changes in the composition of the new camp turned out to be insignificant and did not affect the taste characteristics and did not affect the shelf life extended by such a technique.