Roasting-driven flavor reconstruction in Wuyi Rougui tea: a dual mechanism of pectin-mediated thickening and metabolite remodeling

Roasting shapes the sensory quality of Wuyi Rougui tea, but the links between sensory changes and flavor compound remodeling across roasting stages remain insufficiently characterized. Sensory evaluation and electronic sensory analysis showed that RG2O exhibited enhanced sensory characteristics, including fruity-floral and cinnamon-like aroma attributes. GC-MS analysis identified 362 volatile metabolites, with esters, terpenoids, and heterocyclic compounds as the major classes. OAV and VIP analyses suggested that 1-nonen-3-one, pyrazines, and other differential volatiles may contribute to the variation of mineral and roasted aroma characteristics. Non-volatile analysis showed that gallic acid (GA), gallocatechin gallate (GCG), and theabrownins were associated with taste-related attributes, including thickness, while roasting was accompanied by the conversion of protopectin into soluble pectin. Molecular docking provided predictive evidence for potential interactions between GA/GCG and the calcium-sensing receptor related to kokumi-associated perception. Overall, roasting was associated with coordinated remodeling of volatile and non-volatile metabolites, together with changes in pectin components, contributing to the reconstruction of flavor characteristics in Wuyi Rougui tea.