Widely Targeted Metabolomics Reveals the Quality Characteristics of a New Tea Cultivar, 'Baiyun 0492'

To explore the taste characteristics and flavor characteristics of Baiyun 0492 white tea, Fuyun 6 was used as a comparison to describe and analyze the taste of the tea by the standard tea sensory evaluation method and quantitative descriptive analysis. A total of 1083 nonvolatile metabolites were identified by ultrahigh-performance liquid chromatography and mass spectrometry (UPLC-MS-MS). N-Feruloyl tyramine, with strong biological activity, may be the specific metabolite of Baiyun 0492 white tea, and 3,4,5-tricaffeoylquinic acid, with a bitter taste, may be the specific metabolite of Fuyun 6 white tea. Most of the different metabolite contents were negatively correlated with the Baiyun 0492 and Fuyun 6 white tea grades. KEGG metabolic pathway analysis showed that Baiyun 0492 and Fuyun 6 white teas had higher enrichment levels of flavonoids, caffeine, amino acids and carbohydrate-related metabolic pathways. Correlation analysis using widely targeted metabolomics and quantitative taste description showed that most flavonoid differences and some amino acid and phenolic acid differences were significantly positively correlated with bitterness and astringency, including quercetin-3-o-rhamnoside (quercetin), L-arginine, 3,4,5-tricaffioylquinic acid, and neochlorogenic acid. Some soluble sugars were positively correlated with sweetness, including D-maltose and D-sucrose, which were the key taste components of Baiyun 0492 and Fuyun 6. These metabolites may be responsible for the taste characteristics of Baiyun 0492, which is characterized as sweet and mellow, while the taste of Fuyun 6 is mainly mellow. In this study, a wide range of targeted metabolomics techniques were used to screen out different metabolites related to the quality of Baiyun 0492 and Fuyun 6 white teas, providing a reference for clarifying the quality characteristics of Baiyun 0492.