Analysis of microorganisms and physicochemical properties in Zaopei during the fermentation of Chinese zhijiang-flavor liquor

Abstract

Zhijiang-flavor liquor, one of the most famous strong aroma style of Chinese liquor, is distilled from fermented grains in Hubei province of China. In order to know the diversity, the constitution, and the
dynamic change of microflora and physicochemical components in Zaopei during the fermentation of Chinese Zhijiang-flavor liquor, a normal pit in Zhijiang Distillery in autumn (used as experimental pit) was studied. The analysis and comparison of microorganisms in Zaopei during the fermentation process showed that the microbial genera changed with increasing fermentation time. Knowledge of the microbial diversity provides a basis for understanding the role and the contribution of microbes in
the liquor-production process. More than 200 colonies were isolated and characterized. The isolates were discriminated by phenotypic, conventional biochemical taxonomic methods and bioMerieux Vitek- 32. The presence of bacteria, moulds, yeasts and antinomycetes were revealed. The results showed that bacteria, yeasts, moulds and antinomycetes counts increased significantly during the first 4 days of the fermentation, and the latter three decreased sharply in the following 3 days; the total microbial
population decreased gradually during the 7 and 24 days; the proportion of bacillus to aerobiotic bacteria had a rise after 24 days fermentation. In this study, 5 bacillus isolates were identified with species by VITEK-32 system. The 5 bacillus isolates were Bacillus cereus group, Bacillus
amyloliquefaciens, Bacillus megaterium, Bacillus sphaericus and Bacillus pumilus.