Classification of Pu-erh ripened teas and their differences in chemical constituents and antioxidant capacity

For the scientific classification of Pu-erh ripened teas (PRTs), phytochemical compositions including 14 polyphenolic compounds, 2 purine alkaloids and 18 free amino acids in 24 PRTs were determined by HPLC, respectively. The in vitro antioxidant activities were evaluated by 5 various assays. PCA explaining 38.7% of total variance, HCA and OPLS-DA (R2Y = 0.887, Q2 = 0.873, respectively) could classify PRTs into Puer and Banna groups by production place basically, which caused significant (P < 0.05), highly significant (P < 0.01) or extremely significant (P < 0.001) differences of 29 chemical components. The 19 relevant components used for the identification of storage location through OPLS-DA (R2Y = 0.625, Q2 = 0.601, respectively) were selected. PRTs of various origins, such as production place and storage location, demonstrated significant (P < 0.05) differences in antioxidant activities. Several polyphenolic compounds like (−)-epicatechin, (−)-gallocatechin, rutin and kaempferol contributed to the antioxidant activities. This study helps to understand chemical profile and antioxidant activities of PRTs.