Key Metabolites Influencing Astringency and Bitterness\nin Yinghong 9 Large-Leaf Dark Tea Before and After Pile-Fermentation

Understanding\nthe impacts of pile-fermentation on the taste quality\nof dark tea (DT) is crucial. Although the large-leaf DT, Yinghong\n9 DT, was successfully developed, its taste quality was not systematically\nstudied. This research aims to analyze how pile-fermentation affects\ntaste. Our taste evaluations indicated that pile-fermentation reduces\nastringency while slightly increasing bitterness. Through untargeted\nmetabolomic analysis, we identified 16 key metabolites associated\nwith these taste changes. The analysis of the dose-overthreshold values\naffirmed that rutin, isoquercetin, myricetin 3-galactoside, EGCG,\nDL-C, and ECG were found to lower astringency, while caffeine contributed\nto the slight increase in bitterness. Additionally, the changes in\nthese metabolites are closely linked to the catalytic effects of microbial\nextracellular enzymes. These findings provide a theoretical foundation\nfor a deeper understanding of how pile fermentation influences the\ntaste quality of large-leaf DT.