Abstract:

Tolerance of rice wine yeast is essential for brewing rice wine. In order to breed tolerant rice wine yeast, original yeast strain YS (Saccharomyces cerevisiae) was subjected to ethanol-heat-shock, UV-induced mutagenesis of cells and proptoplasts coupled with high temperature domestication to screen and obtain a mutant yeast YS6.2.5 with normal growth at 30 ℃ for rice wine fermentation. The mutant YS6.2.5 had the characteristics of small size, round shape, good aroma-producing favor and low acid-producing property. The alcohol-producing capability, alcohol tolerance, sugar tolerance of YS6.2.5 were 9.0%, 19% and 30 °Bx at 30 ℃, and 6.5%, 20% and 28 °Bx at 38 ℃, respectively. Fermentation tests showed that the YS6.2.5 had strong physiological tolerance, high fermentation power, stable hereditary, and better industrial application prospect.

Key words: rice wine yeast, tolerance, mutagenesis breeding, thermal effect, protoplast