Correlation between autochthonous microbial communities and flavor profiles during the fermentation of mustard green paocai (Brassica juncea Coss.), a typical industrial-scaled salted fermented vegetable

Mustard green paocai is a salted vegetable product that is fermented with low salt in the initial stage and preserved with high salt in the middle stage. To reveal the key flavor-producing potential of core bacterial and fungal communities during the 365-day fermentation of industrial-scaled paocai. In this study, microbiome and molecular sensory science were used to analyze potential relationships between microbial diversity and key flavor compounds. The results showed that bacteria were more diverse than fungi. High salinity improved the flavor of industrial paocai and simplified the microbial community. A total of 74 bacterial and yeast strains were isolated and identified throughout the fermentation process. Lactiplantibacillus, Halanaerobium, Halomonas, Pseudomonas, and Enterobacteriaceae were the dominant bacterial genera, and Debaryomyces hansenii was the core fungal genera in paocai. 4-Ethylphenol, anethole, butanoic acid, 4-ethylguaiacol, and 3-methyl-1-butanol were identified as key flavor compounds in industrial paocai with odor activity values greater than 1. Spearman correlation analysis indicated that bacteria have a greater impact on the flavor of paocai than fungi. Halanaerobium and Halomonas were correlated with flavor and spoilage in paocai. This study provides guidance for the production of desirable flavors by multi-bacteria synergistic fermentation of industrial paocai.