Comparative analysis of key precursors and metabolites involved in flavor formation of different rapid-fermented Chinese fish sauces based on untargeted metabolomics analysis

•Three rapid-fermented fish sauces (YQ, BWQ, BWE) at various stages were prepared.•6 fatty acids were selected as key flavor precursors of three fish sauces by PLS-VIP.•51, 47 and 45 metabolites were deemed as key components in YQ, BWQ and BWE samples.•Specific metabolites were primarily associated with amino acid metabolism.•Correlations between microbial genera and metabolites was preliminarily explored. Our study aimed to characterize the flavor precursors and metabolite profiles during fermentation of three rapid-fermented fish sauces (koji fermentation (YQ), insulation fermentation with koji (BWQ) and insulation fermentation with enzyme (BWE)) by a comparative metabolomics analysis. The total amount of free amino acids and free fatty acids in BWQ and BWE samples was significantly higher than that in YQ sample during fermentation, and C16:0, C22:6, C18:1, C14:1, C18:0 and C20:5 were deemed as key flavor precursors of three fish sauces. We identified 51, 47 and 45 differential metabolites as crucial components in YQ, BWE and BWQ samples. Specific metabolites in three samples were mainly related to amino acid metabolism, especially histidine, cysteine and methionine metabolism. Furthermore, 5 bacteria genera exhibited positive impacts on the generation of various flavor-related metabolites. This study provides a theoretical basis for targeted control of flavor and quality in the production of rapid-fermented fish sauce.