Dynamic Changes in Bacterial Community, Metabolite Profiles, and Flavor Compounds of Watermelon Soybean Paste During Fermentation

The aim of this study was to investigate the dynamic changes in physicochemical properties, microbial community, metabolite profiles, and volatile compounds in watermelon soybean paste (WSP) during natural fermentation. Results showed that total acids, amino nitrogen, reducing sugar content, and umami-taste amino acids were significantly increased in WSP samples during the fermentation process. Various bacterial communities, including Enterobacter, Bacillus, Staphylococcus, Enterococcus, Weissella, and Lactobacillus, were detected as dominant genera. A total of 804 metabolites, mainly including lipids (18.78%) and amino acids and their derivatives (13.56%), were detected across the different fermentation stages. The correlation analysis between volatile compounds and bacterial community at the genus level revealed that 2-methylisoborneol, 1-octen-3-ol, benzene acetaldehyde, tetramethylpyrazine, and phenylethyl alcohol strongly correlated with Enterococcus, Bacillus, Weissella, and Pseudomonas. This study revealed the dynamics of the bacterial community and volatile compounds in the fermentation process and demonstrated their inter-relationship during WSP fermentation.