Revealing the Differences in Taste/Mouthfeel Quality of Raw Pu-erh Tea Under Different Drying Methods Based on Nontargeted and Targeted Metabolomics

Drying plays a critical role in shaping tea quality. This study systematically investigated the differences in the taste/mouthfeel quality of hot-air drying raw Pu-erh tea (HDRPT), pan-fired drying raw Pu-erh tea (PDRPT), and sun drying raw Pu-erh tea (SDRPT). The results showed that SDRPT exhibited a mellow and thick mouthfeel with a sweet aftertaste, and significantly higher intensities of umami and sweetness compared to PDRPT and HDRPT. The relatively higher contents of amino acids such as theanine, glutamic acid, aspartic acid, and glutamine, along with water-soluble sugars, and relatively lower contents of catechins, including ECG and EGCG, were identified as key material bases contributing to the unique taste/mouthfeel quality of SDRPT. A total of 1987 non-volatile components were detected, from which 137 differential non-volatile components were screened. Among these, 75 components in SDRPT showed significant differences from both PDRPT and HDRPT, with the majority exhibiting higher relative contents in SDRRT, particularly notable among lipids, phenolic acids, and terpenoids. Furthermore, all 75 differential components were significantly correlated with at least one taste/mouthfeel attribute, with most showing significant positive correlations with umami, sweetness, and sourness, and significant negative correlations with bitterness and astringency. These findings provide a theoretical foundation for understanding the mechanism by which drying techniques influence the taste/mouthfeel quality formation of raw Pu-erh tea, and offer a scientific basis for improving its quality.