Environmentally Friendly Beer Brewing: Repaired Gene Improves Commercial Lager Fermentation

Researchers are from VTT Technical Research Center of Finland.

The use of more concentrated, high gravity and very high gravity (VHG) brewer's worts for the manufacture of beer has economic and environmental advantages. By using a special strain of brewer's yeast and adding more sugar, commercial brewers can create a beer with a higher alcohol percentage using the same amount of ingredients.

The resulting concentrated beer can be diluted with water to create a beer with the desired alcohol content. Current strains of brewer's yeasts, however, ferment VHG worts slowly and incompletely, leaving undesirable byproducts in the final beers.

Current research suggests that lager yeast strains possess a faulty gene that causes the brewing problems. Researchers repaired the lager yeast's genes by using DNA sequenced from an ale strain. The new yeast fermented VHG lager wort faster and more completely than unmodified strains, producing beers containing more ethanol and less unwanted byproducts.

"They [the transformed yeasts] fermented VHG wort faster and more completely, producing beers containing more ethanol and less residual maltose and maltotriose," say the researchers.