Integrated sensory, chemical, metabolomic, and antioxidant profiling reveals coordinated quality transformation of Lapsang Souchong black tea during decade-long storage

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Long-term storage of Lapsang Souchong (LS) black tea is traditionally believed to improve its aged flavor and functional quality, but the multi-level changes underlying this process remain insufficiently characterized. In this study, LS black tea samples from eight production years (2013–2023, corresponding to 10 to 0 years of natural storage) were investigated using sensory evaluation, chemical composition analysis, antioxidant activity assays, and multimodal data integration. Electronic tongue profiling and widely targeted UPLC–MS/MS metabolomics were further performed on five representative production years to characterize instrumental taste responses and non-volatile metabolite remodeling. Quantitative descriptive analysis revealed storage-responsive taste changes, with Sour and Smooth increasing during storage and Brisk, Umami, and Sweet decreasing. Among these attributes, Sour showed the strongest monotonic association with storage duration (Spearman r = +0.994). Chemical analysis indicated storage-related tea pigment transformation, especially higher theabrownin levels and lower TR/TB ratios in long-stored samples. Metabolomic profiling identified 183 storage-associated metabolites, revealing prominent changes in lipid-derived compounds, flavonoid- and tannin-related metabolites, and pine-smoking-derived diterpenoids. Notably, abietic acid and dehydroabietic acid were markedly depleted during storage, suggesting that pinewood-smoking-related diterpenoids may serve as characteristic molecular indicators of LS storage transformation. Among the four antioxidant assays, PTIO· scavenging showed a significant negative association with storage duration (Spearman r = −0.810, p = 0.015), suggesting its potential relevance to the depletion or transformation of nitrogen-containing bioactive compounds. Multimodal integration using a single-latent-variable partial least squares regression model captured the major storage-related variation based on 19 predictors, with cross-validated performance of Q 2 = 0.864 and RMSECV = 1.370 years. Twelve predictors showed VIP values greater than 1.0 across sensory, electronic tongue, chemical, metabolomic, and antioxidant modalities. In addition, a simplified composite storage score showed strong concordance with actual storage duration across the eight production years (Spearman r = +0.976, p < 0.001). Overall, these findings indicate that LS black tea storage involves coordinated sensory, chemical, molecular, and functional transformations rather than simple quality deterioration, providing a quantitative basis for storage-related quality evaluation.

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