Abstract:The thermotolerant bacterial flora in Daqu contains various enzyme systems, which considerably influence the production of flavor substances in liquor. The high-temperature enrichment method was used to isolate the target thermotolerant bacterial flora from Daqu, which was subsequently incorporated into bran koji and utilized in the brewing process of Xiaoqu liquor. The functions of the Daqu thermotolerant bacterial flora in Xiaoqu liquor under three high temperature conditions were preliminarily explored. Microbial structure and diversity were analyzed using 16S rDNA sequencing, and the effect of moisture content on bacterial biomass in bran koji was investigated. The results showed that the thermotolerant bacterial flora, dominated by Bacillus, present in Daqu was successfully transferred in bran koji and became dominant. The increase in enrichment temperature within a certain range also led to an increase in the proportion of thermotolerant bacteria. When the moisture content was 55%, the bacterial biomass in bran koji was up to 8.52×1010 CFU/g. Brewing experiments using Xiaoqu liquor revealed that the optimal Xiaoqu liquor produced by brewing led to an increase in the liquor yield by 3.7%, a decrease in the content of higher alcohol by 27.27%, and an increase in the ester content by 23.07%, compared with the control group.
