(ORDO NEWS) — Microbiologists have solved one of the long-standing problems of brewing – making the taste of beer resistant to high pressure during brewing.
To do this, I had to delve into the DNA of brewer’s yeast and edit the code associated with the saturation of taste.
Biologists from 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 flavor.
After genome-editing with CRISPR/Cas9 technology, pressure-boiled yeast produced an average of 145% more aromatic esters.
Historically, beer was brewed in open horizontal containers, but with the rise of beer consumption, brewers have moved to large, closed vessels.
They are easier to fill, empty and clean, and the sealed containers keep germs and contaminants out of the beer and ruining it. Yeast does not like foreign impurities during the fermentation process.
However, large closed vessels are also not ideal for brewing beer. In such vessels, the pressure constantly increases, which affects the fermentation and worsens the taste of the drink.
Excessive pressure reduces the production of isoamyl acetate , an ester that produces a banana (or pear) smell and taste.
Oddly enough, it is this fruity component that makes the overall taste of beer so characteristic and full-bodied.
And it is very sensitive to pressure: already after 0.5 bar (half atmospheric pressure), the production of isoamyl acetate drops exponentially, and at 2.7 bar it stops completely.
In large industrial tanks, the liquid alone creates a hydrostatic pressure of up to 1.8 bar. The 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 cannot be removed quickly. In general, it is hardly possible to completely get rid of the increase in pressure when brewing beer.
You don’t need to, because excess pressure can be useful: for example, it inhibits the formation of fusel alcohols and acetate esters, which is good for the quality of the beer.
Therefore, it makes sense to make the beer taste resistant to high brewing pressure.
Scientists tried to find out which genes in brewer’s yeast are responsible for the production of isoamyl acetate during fermentation.
It turned out that the production of “fruity taste” can be regulated by a single “switch” – a mutation in the MDS3 gene.
Using CRISPR/Cas9 technology, biologists have edited the genome of 423 strains of the brewer’s yeast Saccharomyces cerevisiae , endowing them with the ability to actively produce isoamyl acetate under excessive pressure.
To test the result, the biologists used a homemade brewing apparatus, similar in characteristics to large industrial beer brewing plants.
As expected, genetically modified yeast became less sensitive to CO2 pressure. Even at 1.65-1.8 bar, the production of isoamyl acetate decreased minimally, and on average its production at overpressure increased by 145% relative to conventional yeast.
The researchers are sure 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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