Metabolomics-Based Analysis of Dayezhong Fresh Tea Leaves: Effects of Cultivar and Tenderness on Black Tea Quality

To elucidate differences in fresh-leaf quality associated with cultivar and leaf tenderness at harvest, this study investigated three tea samples: Hainan Dayezhong with one bud and one leaf (1L-HN), Hainan Dayezhong with one bud and two leaves (2L-HN), and Yunnan Dayezhong with one bud and one leaf (1L-YN). Basic physicochemical indices, non-targeted metabolomics, and sensory evaluation were integrated for comprehensive analysis. The results showed that 1L-HN exhibited excellent sensory quality and contained abundant polyphenols and amino acids, thereby providing a material basis for its balanced taste profile. Metabolites such as L-tryptophan, 13(S)-HPOT, and linoleic acid were closely associated with the characteristic floral and fruity flavor of Hainan Dayezhong. Metabolomic analysis further indicated that flavonoid biosynthesis and glycerophospholipid metabolism were the major pathways contributing to the observed metabolic differences. This study provides a theoretical basis for understanding the mechanisms underlying flavor formation in different varieties of black tea.