Identification of the key phytochemical components responsible for sensory characteristics of Hunan fuzhuan brick tea

The flavor of Hunan fuzhuan brick tea (HFBT), as a typical post-fermented dark tea, is one of the crucial properties reflecting its quality and influenced by phytochemical components. However, the key components related to the quality of HFBT remain unclear. Thus, this study investigated the relationship between 6 sensory attributes and 56 phytochemical components of 27 HFBT, and identified key substances using multivariate statistical analysis. Results showed that the quality characteristics of HFBT can be categorized as bitter-astringency, mellow, and umami-sweet type. Among these, bitterness, astringency, and sweetness were dominant. Further, a total of 32 phytochemical components were identified as key contributors to the quality characteristic of HFBT through the partial least squares regression (PLSR) analysis and dose over threshold (Dot) factor, including 8 flavonol glycosides, 7 overall indicators, 5 phenolic acids, 5 amino acids, 4 catechin components, 2 organic acids, and 1 alkaloid. Among them, 19 phytochemical components together influence bitterness, astringency, and sweetness. In conclusion, this study provided a reference base for improving the quality of HFBT, and the subsequent experiment will further explore key components related to sourness, umami, and overall taste especially the isomerism and multivariate taste characteristics of amino acids in dark tea.