不同等级红茶的抗氧化活性及关键成分比较分析

为了分析三个不同等级红茶的抗氧化活性强弱及关键差异成分，该研究检测分析了红茶样品抗氧化活性及主要化学成分的含量。实验结果表明：红茶抗氧化活性随红茶等级的升高呈现出递增趋势，其中特级红茶和二级红茶之间差异达到显著水平（p<0.05）；此外，这五款不同品类红茶间抗氧化活性强弱水平也参差不齐，存在较大差异。检测成分发现，红茶样品内的咖啡碱、多酚、儿茶素、非酯型儿茶素、没食子酸、茶黄素含量随红茶等级升高逐渐增加；而多酚和酯型儿茶素含量变化则与品类间红茶活性变化一致；相关性分析发现红茶的抗氧化活性与多酚、儿茶素、非酯型儿茶素、酯型儿茶素、没食子酸、茶黄素等成分含量具有较强的正相关，其中多酚含量与4种抗氧化活性指标相关性均达到极显著水平（p<0.01），与T-AOC值和DPPH值相关系数均达到0.9以上。综上可知，红茶的等级会对其抗氧化活性造成影响，多酚及其衍生物是决定红茶等级和抗氧化活性的重要指标。

Antioxidant Activity and Key Components of Three Grades of Black Tea

Three grades of black tea were investigated to determine their antioxidant activity and main chemical components. The results showed that the antioxidant activity of black tea samples increased with increasing tea grade, with a significant difference between special-grade and second-grade black teas (p<0.05). In addition, antioxidant activity also varied significantly among five different categories of black tea. Composition analysis revealed that the levels of caffeine, polyphenols, catechins, non-ester catechins, gallic acid, and theaflavins increased gradually with increasing tea grade; whereas the polyphenol and ester catechin levels were consistent with the changes in antioxidant activity among the five different categories of black tea samples. Correlation analysis indicated that the antioxidant activity of black tea was significantly positively correlated with the levels of polyphenols, catechin, non-ester catechin, ester catechin, gallic acid, and theaflavins. Among them, the correlation of polyphenols with the four indicators of antioxidant activity were highly significant (p<0.01), and the correlation coefficients with T-AOC and DPPH exceeded 0.9. In conclusion, the grade of black tea can influence its antioxidant activity, while polyphenols and its derivatives can serve as key components for determining the grade and antioxidant activity of black tea.