Metabolomics Analysis of Difference in Chemical Components among Different Types of Yunnan White Tea

In this study, the difference in the chemical composition among the representative types of Yunnan white tea, Yun Baihao, Yueguangbai grade Ⅰ and Ⅱ of Baimudan and Yun Shou were investigated by metabolomics based on ultra-high performance liquid chromatography-quadrupole orbitrap mass spectrometry (UPLC-Q-Orbitrap-MS). A total of 120 compounds were identified, including catechins, dimeric catechins, amino acids, alkaloids, phenolic acids, organic acids, aroma glycosides, flavonoid glycosides, N-ethyl-2-pyrrolidinone-substituted flavan-3-ols, and lipids. Partial least squares-discriminant analysis (PLS-DA) and heatmap analysis showed that there were distinct differences in the chemical components among the different types of Yunnan white tea. A total of 76 significantly differential compounds were among these types (P < 0.05). The contents of catechins, dimeric catechins, alkaloids, phenolic acids, and theanine were higher in white tea from younger tea leaves; some amino acids and myricetin glycosides were richer in Baimudan, while the contents of apigenin glycoside, kaempferol glycoside, quercetin glycoside and lipid compounds were relatively high in Yunshou. This study can provide a theoretical basis for the studies of sensory quality, nutritional value and grade discrimination of Yunnan white tea.