关键词: 绿茶, 加工, 总酚, 类黄酮, 抗氧化活性

Abstract: 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)μmol/g) after being processing into green tea. No linear relationship was observed between TEAC and total phenol or total flavonoid contents (R2＝0.19, and R2＝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. 

Key words: green tea, processing, phenolics, flavonoids, antioxidant capacity