不同等级烘青绿茶生化成分及抗氧化能力的研究

：目的 研究3个不同等级烘青绿茶的生化成分、感官品质及抗氧化活性。方法 使用分光光度计测定3种茶样中总黄酮、茶多酚、氨基酸和咖啡碱的含量，利用清除二苯代苦味酰基自由基（1,1-dipheny-2-picryhydrazyl free radical, DPPH）法测定了其抗氧化活性，并进行感官评价。结果 3个等级绿茶总黄酮、茶多酚、氨基酸和咖啡碱含量差异显著（P＜0.05），茶多酚随着茶样等级的降低而升高，咖啡碱的含量则相反，而氨基酸和黄酮是波动变化；不同等级绿茶的半抑制浓度（half maximal inhibitory concentration, IC50）差异显著（P＜0.05），且IC50随着等级的降低而下降；感官评价得分随着等级的降低而降低；3种茶的抗氧化活性与其茶多酚含量成极显著正相关P＜0.01），与咖啡碱的含量和感官审评得分呈极显著负相关（P＜0.01）。结论 3个等级的炒青绿茶抗氧化性随着等级的降低而升高，且与其主要生化成分呈显著相关。

Study on the biochemical components and antioxidation ability of different grades of roasted green tea

Objective To study the biochemical components, sensory quality and antioxidant activity of 3 different grades of roasted green tea. Methods The contents of total flavonoids, tea polyphenols, amino acids and caffeine in 3 kinds of tea samples were determined by spectrophotometer. The antioxidant activity was determined by 1,1-diphenyl-2-picryhydrazyl free radical (DPPH) method, and the sensory evaluation was carried out Results The contents of flavonoids, tea polyphenols, amino acids and caffeine in the 3 kind of green tea were significantly different (P<0.05). Tea polyphenols increased with the decrease of tea grade, while the content of caffeine was the opposite, while amino acids and flavonoids fluctuated. The half maximal inhibitory concentration (IC50) of different grades of green tea was significantly different (P<0.05), and IC50 decreased with the decrease of grade. The score of sensory evaluation decreased with the decrease of grade. The antioxidant activities of the 3 kinds of teas were highly significantly positively correlated with the content of tea polyphenols (P<0.01), and highly negatively correlated with the content of caffeine and sensory evaluation score (P<0.01). Conclusion The antioxidant activity of these 3 grades of roasted green tea increases with the decrease of grade, and is significantly correlated with its main biochemical components.