Flavor Changes Through the Fermentation Process of Longmen Rice Vinegar

The flavor profile of Longmen rice vinegar directly influences consumer purchase intention, and understanding its variation during fermentation is crucial for final product quality control. In this study, the flavor dynamics during the fermentation of Longmen rice vinegar were systematically investigated. Sensory evaluation indicated that acidity increased significantly during the acetic acid fermentation stage, while alcoholic and fermented odors decreased continuously. Instrumental analysis identified 129 volatile compounds, predominantly esters, alcohols, and acids. Based on relative odor activity value (r-OAV) analysis, acetic acid, 3-methylbutyl acetate, 2,3-butanedione, benzeneacetaldehyde, phenethyl alcohol, ethyl acetate, 2-phenylethyl acetate, ethyl 4-methyl-pentanoate, 3-methyl-1-butanol, and 3-methylbutanal were determined to be the major contributors to the overall aroma. Orthogonal partial least-squares discriminant analysis (OPLS-DA) further screened 21 key differential compounds. Significant variations in organic acid and amino acid contents during fermentation were also observed. Correlation analysis revealed relationships between key aroma compounds and organic, as well as amino, acids. These findings establish a foundation for monitoring flavor dynamics during the fermentation of Longmen rice vinegar.