Dynamics and Potential Mechanisms of Astringency, Liquor Color, and Key Contributing Compounds During the Roasting Process of Wuyi Rock Tea

Roasting is a critical step in shaping the sensory quality of Wuyi Rock Tea (WRT), particularly in reducing astringency and improving infusion color. However, the dynamic changes and their molecular mechanisms remain insufficiently understood. In this study, sensory evaluation was integrated with metabolomics, quantitative analysis, molecular docking, turbidity assays, and reconstitution/omission experiments to elucidate the effects of roasting. Untargeted metabolomics identified 53 differential metabolites, further correlation analysis identified six potential key compounds, including epigallocatechin, epicatechin, cis-3-O-p-Coumaroylquinic acid, cis-4-O-p-Coumaroylquinic acid, Theasinensin B, and Phloretin-3',5'-di-C-glucoside, as pivotal in jointly modulating both astringency and infusion color. Molecular docking and turbidity measurements indicated their interactions with salivary proteins, supporting their roles in astringency perception, which were further confirmed by reconstitution and omission experiments. Pathway analysis revealed that roasting promoted epicatechin isomerization, degradation, and polymerization, as well as coumaroylquinic acid isomerization, alongside interactions with amino acids and sugars, collectively driving sensory evolution. This study provides the first integrated metabolomics-based insight linking color–astringency evolution with molecular interactions in WRT, offering a scientific basis for optimizing the roasting process to obtain superior sensory properties of WRT. • The perceived astringency of WRT decreased progressively, and the color of the tea liquor gradually deepened, with increasing roasting intensity. • Astringency showed a significant positive correlation with the L* and H°values of the tea infusion color at the WRT roasting process. • Metabolomic analysis of WRT identified 53 differential metabolites (R0–R3 vs. R4–R5), six of which—EGC, EC, cis-3-O-PCoQA, cis-4-O-PCoQA, TSB, and phloretin-3′,5′-di-C-glucoside—were potential key metabolites. • The major transformation mechanisms of differential metabolites during roasting included isomerization, degradation, and polymerization, as well as interactions with amino acids and sugars.