Non-volatile metabolite profiles and taste quality of Pu-erh raw tea on different storage years by metabolomics and 1H qNMR.

Pu-erh raw tea (PRT), a post-fermented tea, is prized for its complex flavor profile and health-promoting properties. While extended storage enhances its sensory attributes, the decade-scale metabolic dynamics underpinning flavor evolution remain unexplored. This study comprehensively characterized non-volatile metabolomic profiles and flavor changes in PRT across a 10-year storage period (2012-2023). Integrated sensory evaluation and electronic tongue analysis indicated progressive darkening of the infusion attributed to oxidation and increased mellowness in aged samples, though instrumental taste differentiation was limited. Untargeted metabolomics identified 3384 metabolites, with 619 consistently present across all storage years. Crucially, γ-linolenic acid and gallic acid demonstrated significant time-dependent accumulation, quantitatively validated via 1H quantitative NMR (qNMR). These metabolites emerged as robust markers for discriminating PRT storage duration, revealing novel biochemical drivers of its long-term aging characteristics.