The succession of procaryotic microbial community and the flavor components in the storage process of Daqu

Abstract:

[Objective] To expound the necessity and importance of the storage process of Daqu, and to control the quality of Daqu, we researched the succession of bacterial community and the flavor components of Daqu. The relationships between different bacterial genera were also analyzed. [Methods] We analyzed the bacterial community structure of Daqu in different storage processes through MiSeq high-throughput sequencing technology; Co-occurrence pattern analysis method was used to analyze the relationships between different genera of bacteria; SPME-GC-MS was used to analyze the flavor compounds of Daqu in different storage processes. [Results] 3 710 OTUs were obtained through MiSeq technology, which classified to 160 genera, 29 phyla. Lactobacillus, Bacillus, Leuconostoc, Thermoactinomyces and Lactococcus were the dominant genera in Daqu, which is the guarantee for the normal fermentation. During the storage process, acids, alcohols, esters and other components which good for the flavor of Chinese liquor were accumulated, while the off-odor compounds such as 4-methyl phenol were constantly reduced. The significant pairwise linear regressions for bacteria and flavor components indicated that lactic acid bacteria was closely correlated to lactic acid, acetic acid and other acid components. Besides acids components, Bacillus was correlated to nitrogen compounds also. [Conclusion] During the storage process, the bacterial community structure of Daqu was adjusted and the flavor components were changed for better flavor. In addition to the environmental factors, the metabolic activity of bacteria is the main influence of the formation of flavor components. Therefore, the storage of Daqu is necessary.