Analysis of bacterial community structure and taste quality of different colored high-temperature Daqu in the Xiangyang region, China

In this study, the differences in bacterial community structure and taste quality among the three different colored high-temperature Daqu (HTD) produced by Enterprise-A were investigated. Furthermore, these HTD were compared to HTD produced by local Enterprise-B. The results revealed yellow HTD of Enterprise-A showed significantly higher bacterial richness and diversity (P < 0.05). The dominant bacterial genera were Bacillus (27.09%), Lentibacillus (21.28%), Kroppenstedtia (12.68%), Thermoactinomyces (8.83%). The electronic tongue detection showed that black HTD presented significantly higher taste attributes, such as sourness, astringency, and bitter aftertaste (P < 0.05). Highly significant positive correlations between Bacillus with umami and saltiness were observed (P < 0.01), while a highly significant negative correlation was found between Bacillus and sourness (P < 0.01). Furthermore, the PCoA and cluster analysis revealed that the three colored HTD samples from the same enterprise were closer to each other. Finally, 84 bacterial strains were isolated from the HTD of Enterprise-A using pure culture methods, including B. amyloliquefaciens, B. licheniformis, Caldibacillus hisashii, and Pediococcus acidilactici. This study provides a greater understanding of the quality of HTD from Enterprise-A and reveals that the production process employed by different enterprises has a greater impact on the microbial community structure of HTD, compared to the differences in temperature during fermentation.