Untargeted metabolomics analysis reveals the dynamic physicochemical properties and flavor profiles of pomegranate–grape composite fruit wine across different fermentation stages

Xinjiang is one of China's major pomegranate-producing regions, renowned for its pomegranates characterized by plump, juicy flesh and an optimal balance of sugar and acidity. Wines crafted from these pomegranates contain elevated levels of bioactive components and exhibit enhanced sensory qualities, demonstrating significant potential in the functional food sector. This study investigated changes in the physicochemical properties and metabolomic characteristics of pomegranate-grape composite wine (PGCW) during fermentation. To this end, the study combined physicochemical analysis with non-targeted metabolomics methods to monitor changes in key quality parameters at different fermentation stages (0, 12, 24, 36, 48, and 60 h). The results confirmed that the physicochemical properties of PGCW are highly correlated with its metabolite profile: pH and titratable acidity are directly related to organic acid metabolism, ethanol content peaked at 8% vol after 60 h of fermentation, and total phenolic and flavonoid levels were maintained at high levels throughout the process. Based on metabolite trends and clustering analysis, the fermentation process can be divided into two stages. KEGG database analysis revealed 118 significantly enriched metabolic pathways, with starch and sucrose metabolism dominating in the early stage, amino acid metabolism dominating in the late stage, and flavonoid biosynthesis synergistically driving the fermentation process. These experimental results provide scientific basis for process optimization of fermentation systems.