The dynamic changes and relationships among microbial community, physicochemical properties and flavor substances in fermented grains of Chinese strong-flavor Baijiu

The dynamic changes of the microbial community and its effect with physicochemical properties and flavor substances in fermented grains (FG) during the fermentation of Chinese strong-flavor Baijiu (CSFB) was analyzed by high-throughput sequencing. The result showed that the whole fermentation process of FG can be divided into early stage (0-15d) and later stage (25-60d). In the early stage (0-15d), microorganisms grew and propagated rapidly, and flavor substances were produced in large quantities. Furthmore, pH, ethanol and starch had great influence on the distribution of microbial communities in FG. In the later stage (25-60d), the microbial community structure was relatively stable and Lactobacillus became the dominant genus, and most of the flavor substances disappeared. While ethanol, hexanoic acid, ethyl hexanoate and ethyl octoate were the main flavor compounds, and the physicochemical factor that distinguish the microbial community of FG at this stage was converted to NH4+. In addition, top10 genera had obvious interaction with physicochemical properties of FG, such as Lactobacillus and Pediococcus were positively correlated with total acid content and negatively correlated with pH. Clostridium had significant positive correlation with 14 genera, and Pediococcus had significant negative correlation with 7 genera. In the fermentation process of CSFB, the most important contributors of ester metabolites were Lactobacillus, Clostridium, Methanosarcina and Bacillus. This study would provide a theoretical basis for the design of effective strategies to control the microbial population and optimize the fermentation process in the production of CSFB.