Variations in Antioxidant Compound Contents and Antioxidant Activity during Processing of Traditional Chinese Green Tea

This research was conducted to investigate variations in the contents of total phenols,total flavonoids,and ascorbic acid,trolox equivalent antioxidant capacity(TEAC) and anti-auto-oxidation activity in traditional Chinese green tea at different stages of processing.The total phenol content in fresh tea leaves was 119.91 mg/g of dry weight and decreased to 100.33 mg/g in green tea.Similar trend was observed for total flavonoid content,which decreased from 2.90 mg/g to 2.04 mg/g.Moreover,both classes of compounds decreased mainly at the moisture regain stage.In addition,a gradual decrease(from 4.17 mg/g to 2.95 mg/g) in ascorbic acid content was observed.Fresh tea leaves showed a slight decrease in TEAC(from(524.94 ± 18.68)μmol/g to(487.03 ± 17.97)μ mol/g) after being processing into green tea.No linear relationship was observed between TEAC and total phenol or total flavonoid contents(R 2 =0.19,and R 2 =0.01,respectively).The anti-auto-oxidation activity of green tea was higher than that of fresh tea leaves and the inhibitory rate increased from 52.45% to 78.12%.Therefore,the contents of the main antioxidant compounds decreased and the antioxidant activity changed slightly during the processing of traditional Chinese green tea.