Correlations between characteristic flavor substances and microbial diversity in Guizhou Douchiba

Douchiba, a unique fermented food of Douchi in Guizhou, China, is well known for its rich and long-lasting flavor and dark-oily appearance. However, flavor substances and microbial community of Douchiba and the correlations between them are poorly understood. In this study, the differences in taste components, volatile flavor substances, and microbial diversity of Douchiba from seven regions and corresponding correlations were explored. Taste components in Douchiba were mainly sweet and bitter amino acids, succinic acid, and lactic acid. A total of 71 volatile compounds were identified and the main volatile flavor contributors were mainly classified into acids, pyrazines, and esters. Notably, 29 characteristic compounds were screened via OPLS-DA and VIP analysis, including tetramethylpyrazine, tartaric acid, isovaleric acid, and glutamic acid. The bacterial communities (mainly Bacillus) dominated over fungi. Tetragenococcus and Aspergillus were the core genera. The correlation analysis confirmed that Bacillus exhibited the significant correlations with pyrazines mainly generated via biotransformation and Maillard reaction pathways, whereas Aspergillus synergistically enhanced acidic compounds through carbohydrate metabolism. These findings provide novel insights into the microbial-driven flavor formation mechanism and a theoretical basis for screening industrial starter cultures and flavor regulation in Douchiba.