EFFECT OF TEMPERATURE ON ETHANOL PRODUCTIVITY AND RESISTANCE OF CRYOPHILIC WINE YEASTS

Effects of incubation temperature and ethanol concentration on cell vi ability of two strains of cryophilic wine yeasts YM-84 and YM-126 were compared with those of mesophilic wine yeasts W3 and OC-2. The cryoph ilic wine yeasts showed certain cell viability in the presence of 10% ethanol at 8-degrees-C, the same as the mesophilic wine yeasts. At 25- degrees-C, however, viable cell numbers of these cryophilic wine yeast s were decreased, and this tendency became more marked with the presen ce of ethanol. Comparison of the composition of fatty acid in cells, Y M-84 and YM-126 showed higher proportions of myristic acid to fatty ac id, in addition to higher ratios Of C-16 fatty acids to C18 fatty acid s. These phenomena suggest that these strains have different adaptatio n mechanisms against temperatures. Five strains of cryophilic wine yea sts selected in our culture collection showed the same fermentation ve locity at the low temperature of 7-degrees-C as did YM-84 and YM-126, and at 28-degrees-C their ethanol yields were reduced. From these resu lts, it can be concluded that good fermentability at low temperatures accompanied by production of low amounts of ethanol at intermediate te mperatures is one of the fermentation characteristics observed among c ryophilic wine yeasts.