Alternative Saccharomyces interspecies hybrid combinations and their potential for low ‐temperature wort fermentation

Abstract The lager yeast hybrid (S. cerevisiae x S. eubayanus) possesses two key characteristics that are essential for lager brewing: efficient sugar utilization and cold tolerance. Here we explore the possibility that the lager yeast phenotype can be recreated by hybridizing S. cerevisiae ale yeast with a number of cold tolerant Saccharomyces species including S. arboricola, S. eubayanus, S. mikatae and S. uvarum. Interspecies hybrids performed better than parental strains in lager brewing conditions (12 °C and 12 °P wort), with the S. mikatae hybrid performing as well as the S. eubayanus hybrid. Where the S. cerevisiae parent was capable of utilizing maltotriose, this trait was inherited by the hybrids. A greater production of higher alcohols and esters by the hybrids resulted in production of more aromatic beers relative to the parents. Strong fermentation performance relative to the parents was dependent on ploidy, with polyploid hybrids (3n, 4n) performing better that diploid hybrids. All hybrids produced 4‐vinyl guaiacol, a smoke/clove aroma generally considered an off flavour in lager beer. This characteristic could however be eliminated by isolating spore clones from a fertile hybrid of S. cerevisiae and S. mikatae. Results suggest that S. eubayanus is dispensable when constructing yeast hybrids that express the typical lager yeast phenotype.
Source: Yeast - Category: Molecular Biology Authors: Tags: Special Issue ‐ Yeast interspecies hybrids Source Type: research