Abstract
Lipids are key precursors of aroma-active compounds and essential nutrients in Yu Jiaosuan (YJS), a traditional Chinese fermented fish product. This study evaluated the effects of co-inoculating Lactiplantibacillus plantarum Y279 and Weissella cibaria Y113 on microbial succession, lipid metabolism, and flavor formation during loach YJS fermentation. The inoculated group (HY) showed rapid acidification and effective suppression of spoilage bacteria, with Lactiplantibacillus and Weissella emerging as dominant functional taxa. Untargeted lipidomics identified 1224 lipid species, indicating accelerated triglyceride degradation and enhanced accumulation of lysophospholipids (LPC and LPE) in HY samples. Pathway enrichment analysis revealed intensified glycerophospholipid metabolism and unsaturated fatty acid biosynthesis, providing key precursors for aroma development. Flavoromics detected 213 volatile compounds, with HY samples exhibiting increased esters and ketones and reduced fishy aldehydes. Multivariate and correlation analyses revealed a microbiota-lipid-flavor regulatory network linking lactic acid bacteria to lipid-derived aroma precursors. Sensory evaluation further confirmed enhanced umami intensity, aroma complexity, and reduced off-flavors. Overall, targeted co-inoculation effectively improved YJS quality through coordinated lipid remodeling and flavor maturation.