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

Abstract

Understanding the impacts of pile-fermentation on the taste quality of dark tea (DT) is crucial. Although the large-leaf DT, Yinghong 9 DT, was successfully developed, its taste quality was not systematically studied. This research aims to analyze how pile-fermentation affects taste. Our taste evaluations indicated that pile-fermentation reduces astringency while slightly increasing bitterness. Through untargeted metabolomic analysis, we identified 16 key metabolites associated with these taste changes. The analysis of the dose-overthreshold values affirmed that rutin, isoquercetin, myricetin 3-galactoside, EGCG, DL-C, and ECG were found to lower astringency, while caffeine contributed to the slight increase in bitterness. Additionally, the changes in these metabolites are closely linked to the catalytic effects of microbial extracellular enzymes. These findings provide a theoretical foundation for a deeper understanding of how pile fermentation influences the taste quality of large-leaf DT.