Metabolism profiles of polyphenols and their contribution to taste attributes in oolong teas

Bitterness and astringency are key sensory attributes affecting the taste quality of oolong tea and are closely associated with polyphenols. However, the contribution of polyphenols to the taste differentiation of different oolong tea products remains insufficiently understood. This study aimed to identify and validate the key polyphenols responsible for the taste characteristics of representative oolong teas by integrating quantitative descriptive analysis, metabolomics, dose-over-threshold factors, molecular docking and taste addition tests. A total of 1446 polyphenols were identified, among which 110 differential polyphenols were screened across the three oolong teas. The OPLS model and correlation analysis identified 58 sensory-associated differential polyphenols, most of which were positively correlated with bitterness and/or astringency. Through absolute quantification combined with DOT values, nine potential bitter-active compounds and eight potential astringent-active compounds were screened. Sensory validation further supported theaflavin-3-gallate, theaflavin-3,3′-digallate, gallic acid, quercetin, quercetin-3-O-rutinoside, and kaempferol-3-O-rutinoside as the critical bitter-astringent contributors. Molecular docking further suggested that theaflavin-3-gallate and theaflavin-3,3′-digallate may act as dual bitter-astringent contributors through favorable interactions with bitter taste receptors and salivary proline-rich protein. This study establishes a polyphenol-centered evidence chain linking chemical composition, sensory perception, and molecular interactions, providing candidate markers for regulating the bitter-astringent taste of oolong tea.