Multi-Variety Metabolomic Profiling Uncovers Conserved and Divergent Metabolites Underlying Antioxidant Potential in Grape Dehydration

To characterize and compare metabolic profiles in fresh grapes and corresponding raisins, we performed nontargeted metabolomics analysis of four grape varieties distinct in color and shape. Comparative sugar analysis showed elevated total sugar concentrations in raisins. Black Currant showed highest glucose (304.17 mg/g), while Lanbaoshi exhibited maximum fructose (495.91 mg/g). Further, antioxidant capacity analysis revealed significant increase in all varieties, with Hongxiangfei showing the highest increase. multivariate statistical analyses including PCA and OPLS-DA showed distinct clustering between fresh and dried grapes. In each varieties metabolites ranged from 501–592 changed significantly. Chemical class analysis revealed that lipids were the most common type of different metabolites, followed by phenylpropanoids and organic acids. Integrated pathway analysis showed that different metabolic strategies were linked to the color of the berries. Dark varieties like Black Currant and Lanbaoshi focused on moving phenylpropanoids flux toward anthocyanins, while the green-berried Sultanina focused on making lignans. Trehalose emerged as a critical antioxidant exhibiting a strong correlation with epigallocatechin gallate accumulation. Biomarker analysis revealed EGCG as the principal factor influencing antioxidant potential, while catechin exhibited a strong correlation with ABTS activity. These findings showed first global and variety-specific metabolomic signature of raisin formation, offering a scientific basis for quality optimization and variety selection.