Targeted Metabolic Analysis of Mulberry Wine From Different Vintages and Identification of Oxidative Markers

To investigate evolution trends of metabolite levels in mulberry wine across vintages and identify crucial oxidative markers, this study systematically analyzed the anthocyanins, non-anthocyanin phenols, volatile compounds, chromatic attributes, electrochemical parameters, and antioxidant capacity of mulberry wines from seven vintages, and oxidative markers were screened through correlation analysis between metabolites and electrochemical parameters. Results indicated phenolic compounds and antioxidant capacity generally decreased with shifting to earlier vintages, accompanied by corresponding increases in electrochemical peak potential, reflecting heightened oxidation. A sharp decline in chromaticity was observed after 2 years, coinciding with the nearly complete degradation of monomeric anthocyanins and the emergence of vinylphenolic pyranoanthocyanins as the predominant pigments. The proportions of the highly oxidation-sensitive flavanols and hydroxycinnamic acids decreased by 86.86% and 76.91% over the 11 years, respectively. Simultaneously, earlier vintage wines exhibited significant accumulation of esters and volatile phenols, whereas the alcohols and terpenes content markedly decreased. Furthermore, correlation analysis identified 19 potential oxidative markers, including 14 phenolic compounds (catechin, chlorogenic acid, rutin, gallic acid, ferulic acid, caffeic acid, resveratrol, and astragalin, among others) and five volatile components (ethyl lactate, diethyl succinate, furfural, ethyl 2-hydroxy-4-methylpentanoate, and ethyl 3-hydroxybutyrate). Most of these oxidation markers remained relatively stable within 2 years but underwent a marked shift thereafter, suggesting that two years of aging may be a critical turning point in the oxidation process of mulberry wine. This study provides a theoretical basis for systematically understanding the molecular basis of mulberry wine oxidation from a vintage variation perspective.