Identification and Astringent Effects of Key Astringent Polyphenols in Camellia ptilophylla Tea

This study investigated the astringency of Camellia ptilophylla green tea, using Yunnan large-leaf green tea as a control. Sensory evaluation and turbidity and fluorescence quenching methods based on artificial saliva were combined to compare the astringency intensities of the two teas. High performance liquid chromatography (HPLC) was employed to analyze changes in the concentration of the major polyphenols after artificial saliva treatment identifying the major astringent polyphenol monomers. The interactions between these polyphenols and a salivary protein model were further explored using fluorescence spectroscopy and molecular docking. Non-targeted metabolomics based on high-resolution mass spectrometry was used to identify other astringent polyphenols. The results showed that C. ptilophylla green tea exhibited stronger astringency than did Yunnan large-leaf tea, with gallocatechin gallate, 1,2,4,6-tetragalloyl glucose, and gallocatechin-3,5-digallate identified as the major astringent polyphenols. These polyphenols interacted with the salivary protein model predominantly through hydrophobic interactions and hydrogen bonding. Additionally, myricetin, emodin and taxifolin also showed high binding affinity to the salivary protein model. This study provides insights into the chemical basis for the astringency of C. ptilophylla green tea and lays the groundwork for further research into the mechanism underlying its astringency and for exploring strategies to improve its flavor.