Characterization of dynamic flavor profiles in Yibin Yacai under two fermentation processes via untargeted metabolomics and flavoromics

This study comprehensively characterized the dynamic flavor profiles of Yibin Yacai under traditional dry-salted (LG) and salt-fermented (YZ) processes using untargeted metabolomics and flavoromics. Non-volatile metabolites and volatile compounds were analyzed via LC-MS/MS and HS-SPME-GC × GC-TOFMS, respectively. A total of 751 metabolites and 346 volatile compounds were identified. Significant differences in metabolite profiles were observed: YZ samples showed gradual accumulation of lipids, carbohydrates, and esters, while LG samples exhibited higher levels of amino acids and key flavor compounds (e.g., 1-hexanol, furfural). Sensory evaluation revealed superior sweetness, fruitiness, and floral notes in LG6. YZ6's high fattiness may stem from lipid accumulation during salt-fermentation. Processing critically shapes sulfur compounds, decreasing in LG but accumulating in YZ due to distinct microbial activities. KEGG pathway analysis indicated divergent metabolic transformations: LG samples enriched phenylpropanoid biosynthesis and arginine/proline metabolism, while YZ samples activated shikimate-derived alkaloid and aromatic amino acid pathways. Correlation analysis highlighted strong associations between characteristic non-volatile metabolites (e.g., campesterol, 5-hydroxy-L-tryptophan) and volatile compounds (e.g., β-myrcene, D-limonene), with phenolic derivatives (4-ethylphenol) closely linked to amino acid metabolism. These findings elucidate the molecular basis of flavor formation in Yibin Yacai and provide insights for optimizing fermentation processes to enhance product quality.