Elucidating temporal variations in non-volatile metabolites during black tea rolling process via metabolomics combined with multivariate statistical analysis.

Rolling is a critical determinant of black tea quality, yet temporal metabolite dynamics during this stage remain poorly understood. This study employed UHPLC-Q-Exactive-MS-based untargeted metabolomics to systematically investigate metabolic changes across six sequential rolling intervals (T1-T6). A total of 115 non-volatile metabolites were identified, dominated by flavonol and flavonol/flavone glycosides (30.4%) and amino acid derivatives (25.2%). Pairwise comparative analysis revealed the T3-T4 period as the critical biochemical transition phase. Temporal profiling indicated distinct trends: prolonged rolling progressively reduced flavan-3-ols and phenolic acids, lowering astringency and sourness of tea infusion, while theaflavins increased markedly, enhancing the brightness and mellow taste. These divergent responses highlight the differential effects of mechanical stress on metabolite dynamics. KEGG pathway analysis further identified flavonoid biosynthesis as the primary regulatory pathway governing flavor-related metabolic formation during rolling. The findings provide a scientific framework for optimizing rolling protocols and advancing precision control in black tea production.