Integration of volatile flavor metabolomics and metagenomics reveals microbial-enzymatic pathways governing key aromatic volatile compound biosynthesis in <i>Hongqujiu</i> fermentation

The anabolic pathways of key volatile flavor compounds (VFCs) in <i>Hongqujiu</i> (HQJ) remain insufficiently elucidated. In this study, dynamic changes in volatile flavor profiles and microbial communities throughout HQJ brewing, were systematically investigated using an integrated multi-omics strategy combining metabolomics, flavoromics and metagenomics. The results demonstrated that the ethanol content, titratable acidity, amino nitrogen and higher alcohols increased progressively throughout fermentation. Quantitative flavor metabolomic profiling identified 18 key VFCs, maining comprising ethyl esters, acetate esters and higher alcohols. Metagenomic sequencing revealed that <i>Weissella</i>, <i>Lactobacillus</i>, <i>Saccharomyces</i>, <i>Aspergillus</i>, <i>Talaromyces</i> and <i>Monascus</i> were the predominant microbal genera throughout HQJ fermentation. Functional gene annotation further indicated that key enzymes involved in flavor metabolism are primarily associated with <i>Lactobacillus</i>, <i>Aspergillus</i>, <i>Talaromyces</i>, <i>Saccharomyces</i>, <i>Cyberlindnera</i> and <i>Monascus</i>. Overall, this study elucidates the microbial-enzymatic basis of VFC biosynthesis and establishes a comprehensive flavor metabolic framework for HQJ fermentation, providing a theoretical foundation for aroma quality improvement.