Abstract:By detecting the differences in the contents of 10 main antioxidant?active substances, including caffeine and epigallocatechin gallate, through high-performance liquid chromatography (HPLC), and evaluating their antioxidant capacity comprehensively by DPPH radical scavenging rate, hydroxyl radical scavenging rate, and total antioxidant capacity, this study explored the relationship between the chemical composition and antioxidant capacity of different origin green teas in Guangxi. The results showed that that the content of caffeine in tea was between 17.08 mg/g and 37.16 mg/g; the content of theobromine was around 5 mg/g; the content of theophylline was low (between 0 mg/g and 0.47 mg/g); the content of epigallocatechin gallate was between 10 mg/g and 20 mg/g; the content of epigallocatechin gallate was high, around 50 mg/g; the content of epicatechin gallate was variable, ranging from 2.14 mg/g to 21.2 mg/g; the content of epicatechin was around 5 mg/g; the content of gallic acid and epigallocatechin gallate was low (≤5 mg/g); the content of epigallocatechin gallate was basically below 2 mg/g. Combining the results of similarity evaluation and clustering analysis, green tea from the high and middle latitudes regions of Guangxi was highly similar, that could be clearly distinguished from the low latitudes regions. The DPPH radical scavenging rate of all teas was above 60%; the hydroxyl radical scavenging rate ranged from 1.68% to 85.38%; the total antioxidant capacity was between 1.644 mmol/g and 3.608 mmol/g. Overall, these results show that green tea from Guangxi has good antioxidant activity on average, and the content of polyphenols is positively correlated with its antioxidant activity. This study provides data for the quality evaluation and differential analysis of Guangxi green tea.
