Effect of temperature on ethanol productivity and resistance of cryophilic wine yeasts.

Abstract

Effects of incubation temperature and ethanol concentration on cell viability 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 cryophilic wine yeasts showed certain cell viability in the presence of 10% ethanol at 8°C, the same as the mesophilic wine yeasts. At 25°C, however, viable cell numbers of these cryophilic wine yeasts were decreased, and this tendency became more marked with the presence of ethanol. Comparison of the composition of fatty acid in cells, YM-84 and YM-126 showed higher proportions of myristic acid to fatty acid, in addition to higher ratios of C16 fatty acids to C18 fatty acids. These phenomena suggest that these strains have different adaptation mechanisms against temperatures. Five strains of cryophilic wine yeasts selected in our culture collection showed the same fermentation velocity at the low temperature of 7°C as did YM-84 and YM-126, and at 28°C their ethanol yields were reduced. From these results, it can be concluded that good fermentability at low temperatures accompanied by production of low amounts of ethanol at intermediate temperatures is one of the fermentation characteristics observed among cryophilic wine yeasts.