Characterization of physicochemical properties, volatile compounds, and microbial diversities of inoculated Qingke bean paste.

Qingke, a specialty cereal from the Tibetan Plateau, is known for its rich content of proteins, polyphenols, β-glucan, and other bioactive compounds. The incorporation of Qingke powder into soybean paste enhances both its flavor and nutritional profile. However, there is a need to deepen the understanding of how microbial communities and physicochemical changes contribute to the flavor and nutritional characteristics of Qingke-based fermented products. This study investigated the physicochemical properties, volatile compounds, and microbial community dynamics in Qingke bean paste (QBP) throughout the fermentation process. Significant increases in titratable acid, amino acid content, and enzyme activity were observed over the fermentation period. The dominant microorganisms identified included Bacillus, Pediococcus, Issatchenkia, and Aspergillus. Although the abundance of both Bacillus and Aspergillus gradually decreased, the abundance of Pediococcus and Issatchenkia increased. Redundancy analysis revealed salinity and moisture as the primary factors driving microbial community changes. Spearman's correlation analysis demonstrated a strong positive relationship between the volatile compounds in QBP and the presence of Bacillus and Issatchenkia, indicating their key roles in flavor development. This study provides valuable insights into the taxonomic shifts in microbial communities and the formation of flavor metabolites during QBP fermentation, offering a foundation for further advancements in the processing of Qingke-based products.