Determination of Gallic acid, Epicatechin and Epicatechin gallate in Different Varieties, Manufacturers and Grades of Tea by HPLC-DAD

Tea has been recognized by scientists for its health benefits and disease prevention. But there are many varieties of tea, and its quality is affected by many factors. The quality of tea determines its effects of health care and disease prevention, and gallic acid, epicatechin and epicatechin gallate are the main active ingredients in tea. The goal of this study was to detect the contents of gallic acid, epicatechin and epicatechin gallate in 33 batches of tea from the market by HPLC to explore the effects of these factors on the chemical composition of tea such as different varieties, different manufacturers and different grades. After the analysis of tea samples by HPLC, the relative standard deviations for precision, repeatability, stability and average recovery were acceptable, and the average recovery rates of gallic acid, epicatechin and epicatechin gallate were 100.2, 101.57 and 102.69, respectively. The results showed that gallic acid, epicatechin and epicatechin gallate were detected in both green tea and oolong tea, while epicatechin was not contained in black. The content of gallic acid and epicatechin gallate in green tea was higher than that in oolong and black tea. The composition content of some special grade tea was lower than that of first or second grade tea. Therefore, the results of this study provide a reference for people to choose high-quality tea and reasonable quality control of tea.