中国绿茶传统加工过程中抗氧化物质含量及抗氧化活性的变化

研究中国绿茶传统加工过程不同工艺阶段茶汤总酚、总黄酮、抗坏血酸含量和抗氧化能力的变化。加工成品的总酚含量从鲜叶的119.91mg/g(以干质量计)下降到100.33mg/g，总黄酮含量也有相似的变化趋势，从2.90mg/g下降到2.04mg/g，且这两种成分的降低主要发生在“回潮”阶段。此外，加工过程中茶汤抗坏血酸含量也逐渐下降(从4.17mg/g降至2.95mg/g)。尽管经过剧烈的加工，鲜叶总抗氧化能力(TEAC)仅出现轻微降低，TEAC从(524.94±18.68)μmol/g降至成品中的(487.03±17.97)μmol/g，但总酚和总黄酮与TEAC无线性关系(R2=0.19，R2= 0.01)，而DPPH自由基与总酚和总黄酮有较好的线性关系(R2=0.77，R2=0.56)。此外，加工过程中茶叶抗自动氧化能力增强(抑制率从52.45%增加至78.12%)。表明中国绿茶传统加工过程导致成品茶汤主要抗氧化物质含量的减少，但仅导致其抗氧化能力的轻微改变。

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.