Dynamic analysis of microbial community, flavor components of low-salt fermented red pepper sauce and exploring the key flavours formation

Fermented red pepper (FRP) sauce serves as a representative condiment, and the traditional fermentation of FRP requires high salt content, which is detrimental to human health, thus developing low-salt FRP is a trend. However, the effects of low-salt fermentation on quality and flavor substances in FRP sauce are poorly understood. The aim of this study is to reveal the dynamic changes of microbial community and flavor compounds in low-salt FRP sauce, analyze the interactions between microorganisms and key flavor compounds, and characterize the metabolic pathways of the main flavor components. The results showed that Levilactobacillus, Companilactobacillus and Candida were the core dominant genera in low-salt FRP sauce based on the analysis of the data of amplicon sequence variants. Further, the amplicon data were subjected to spearman correlation analysis found that Levilactobacillus was negatively correlated with other genera, while Companilactobacillus was proved to be remarkably positively correlated with other microorganisms at the strain level. Additionally, 18 volatile compounds and 40 non-volatile compounds were identified as the key flavor substances by HPLC, HS-SPME-GC-MS and UHPLC-QE-MS. Finally, combined metabolomics and metagenomics data revealed that the metabolism of various amino acids was the main pathway for flavor formation, and Companilactobacillus and Candida were significantly positively correlated with flavor formation, which were therefore identified as the core genera for flavor production. These findings deepened our understanding of the effects of low-salt fermentation on microbial communities and flavor metabolites in FRP sauce, which will accelerate the development of reduced-salt fermented foods in the future.