Isolation and Identification of Cold Adaptive Yeast and Its Influence on the Quality of Low Temperature Brewing Rice Wine

In order to screen yeast strains suitable for low-temperature brewing rice wine, this study isolated and purified and screened yeast with comfortable aroma production, excellent fermentation capacity, alcohol production capacity and ester production capacity at low temperature from rice bent, and identified the strain by morphological observation and molecular biology methods, analyzed its growth and tolerance, and applied it to low-temperature brewing rice wine. The results showed that a low temperature tolerant yeast strain XQ2-8 was isolated and screened, which was identified as Saccharomyces cerevisiae. Compared with the control strain, strain XQ2-8 had a shorter delayed growth curve and higher biomass when reaching the stable phase at 15 ℃, and had better low-temperature tolerance characteristics. The strain XQ2-8 was tolerant to the growth environment and could grow normally under the conditions of ethanol volume fraction 8%vol, glucose content 60%, pH3.0 and low temperature 10 ℃. When rice wine was brewed using strain XQ2-8, the total ester content (60.08 mg/L) and glycerol content (2.59 g/L) of low-temperature rice wine increased by 15.6% and 22.7%, respectively, the total acid content (1.91 g/L) and total higher alcohol content (578.20 mg/L) decreased by 18.0% and 17.7%, respectively, compared with room temperature brewing, and the sensory score (89.47) increased by 11.7%. This indicates that low temperature brewing using the screened strain XQ2-8 can improve the low ester content and high higher alcohol content in rice wine and improve the quality of rice wine.