A new source to obtain lager yeast strains adapted to very high gravity brewing: 2-deoxy-D-glucose resistant clones with fermentative capacity of up to 25 °Plato

摘要

Very high gravity brewing (VHGB) usually leads to poor fermentation performances. Constitutively derepressed clones, with capacity of metabolising maltose in the presence of glucose, and thus resistant to 2-deoxy-D-glucose (2DG), may be a solution. A new strategy for the isolation, selection and screening of 2DG resistant clones adapted to VHGB has been developed. Those clones with the highest scores in solid media, liquid cultures and mini-fermentations selections and screenings were tested in very high gravity (VHG) worts (25 °P) in 2-liter EBC tubes. Some showed better fermentation rates than the original lager strains while maintaining beer quality, yeast viability and genetic stability. Thus, 2DG resistant clones are a convenient source for lager yeast strains with improved fermentation capacities in VHGB conditions.