Characterization and correlation of dominant bacteria and volatile compounds in post-fermentation process of Ba-bao Douchi.

Ba-bao Douchi, traditionally produced and spontaneously fermented for 1-2 years, has a unique flavor. However, little information is known about microorganisms and volatile flavors, particularly their relationship. In this study, the aroma profiles including the key aroma compounds, and bacterial communities were characterized and the correlations between dominant bacterial genera with key aroma compounds were studied during the post-fermentation of Ba-bao Douchi. The research showed that 12 bacterial genera were identified as the dominant genus by high-throughput sequencing. A total of 84 volatile compounds were detected by HS-GC-IMS and HS-SPME-GC-MS. Odor activity value (OAV) and gas chromatography-Mass spectrometry-olfactometry (GC-MS-O) were combined to determine the key volatile compounds, and the main volatile compounds including ethyl hexanoate, ethyl heptanoate, isovaleraldehyde, (+)-α-pinene, beta-phellandrene, were found to be responsible for the strong fruitiness, chocolate fragrance, fresh scent flavor, and ginger flavor of Ba-bao Douchi. Pearson correlation analysis showed that 5 dominant bacterial genera were positively associated with > 6 key volatile compounds (p < 0.01, |r| > 0.7). Thus, these bacterial genera might have an effect on the biosynthesis of volatile components. This study provides a theoretical reference for revealing the functional microorganisms and improving the flavor quality of Ba-bao Douchi.