Metabolomic analysis of microbial effects on quality and metabolite conversion in rapidly fermented salt-free shrimp by-product sauce

This study employed single- and multi-strain inoculation strategies using <i>Aspergillus oryzae</i>, <i>Lactococcus lactis</i>, and <i>Hanseniaspora opuntiae</i> to develop a rapid, salt-free fermentation process for South American white shrimp by-products. The physicochemical properties, flavor characteristics, and metabolite profiles of the resulting shrimp by-product sauces were comprehensively analyzed. Among the fermentation groups, the three-strain composite group (YLA) demonstrated superior quality, with elevated levels of free amino acids, TCA-soluble peptides, and organic acids, and reduced total volatile basic nitrogen, contributing to a distinct umami-sweet flavor profile. Metabolomics analysis revealed that microbial synergistic interactions enhanced the biosynthesis of amino acids, unsaturated fatty acids, nucleotides, and aromatic volatiles. Correlation analysis further identified 4-aminobutanoate, dCMP, and ADP-ribose as key metabolites positively linked with umami intensity and overall sauce quality. These findings elucidate the microbial mechanisms underlying flavor compound formation and provide a theoretical basis for the high-value utilization of shrimp by-products in fermented seasoning production.