Co-fermentation of Ganpu tea with Chachi peel alters its chemical profile, reducing certain compounds while increasing others, thus enhancing its unique flavor.
In the research, the effects of Chachi peel cofermentation on the chemical profile of Ganpu tea were examined using an ultra-high-performance liquid chromatography-Q Exactive Orbitrap mass spectrometry (UHPLC-QE Orbitrap MS)-based qualitative and quantitative method combined with multivariate analysis. A total of 171 compounds were identified using a three-level strategy, including seven phenolic acids, 11 flavan-3-ols, and 27 flavonoids and flavonoid glycosides identified in pu-erh tea for the first time.
The principal component analysis (PCA) of untargeted metabolomics and orthogonal partial least squares discriminant analysis (OPLS-DA) models of targeted components revealed significant differences in the chemical profiles between raw pu-erh tea and Ganpu tea. The cofermentation process significantly reduced the total contents of phenolic acids, flavan-3-ols, and flavonoid aglycone. However, most of the quercetin glycosides, myricetin glycosides, and vitexin increased significantly. Additionally, hesperidin, a flavonoid glycoside only found in Chachi, was detected in pu-erh tea for the first time after cofermentation.
Hence, this process clearly impacts the chemical composition and content changes in pu-erh tea, suggesting that cofermentation accelerates the fermentation of pu-erh tea and improves its unique taste.
