Breeding Yeasts for Brewing

Hybrid yeast strains of two types were examined for the rates at which they attenuated brewer's wort in small fermentations. The first class of hybrids were crosses between brewing yeasts and haploid strains of genetically marked laboratory stock. Three of the six hybrids of this type brought about more rapid attenuation of wort than both parent strains from which they were bred. These hybrids are usefulbecause of the genetic markers which they carry. Thesecond group were crosses between pairs of brewing yeasts. Of the 19 hybrids of this type examined, only one proved to attenuate wort more rapidly than both parent brewing yeasts. Another nine hybrid strains attenuated wort at rates intermediate between their two parent strains. It is suggested that the more promising hybrids are suitable strains from which to develop hybrid brewery yeasts by further breeding.