HPLC分析Cu~(2+)对茶酶源酶促氧化合成茶黄素的影响

为比较不同浓度Cu2+处理下茶树鲜叶多酚氧化酶对酶性合成茶黄素效率的影响。通过测定茶叶样品中多酚氧化酶的质量分数,并对氧化产品进行HPLC分析。结果表明,不同浓度Cu2+处理下茶黄素合成效率呈线性变化。n(Cu2+)/n(PPO)=0.2时,茶黄素合成率最高,为35.193%,乙酸乙酯层茶黄素质量分数为45.738%。n(Cu2+)/n(PPO)=0.8时,茶鲜叶多酚氧化酶氧化效果与n(Cu2+)/n(PPO)=0时相当。n(Cu2+)/n(PPO)0.8时,Cu2+增加可抑制茶树鲜叶多酚氧化酶活性。分析儿茶素转化率可知,n(Cu2+)/n(PPO)=0.4时,儿茶素转化率最高,达99.05%;n(Cu2+)/n(PPO)0.4时,儿茶素转化率呈下降趋势。总体而言,n(Cu2+)/n(PPO)=0.2时,茶多酚氧化酶氧化合成茶黄素有最优值。

Cu2+ Effect on Tea Poly-phenol Oxidase Enzymatic Oxidation Synthesizing Thea-flavins with HPLC Analysis

Under gradient concentration Cu₂₊ condition, the effect of tea poly-phenol oxidase on the efficiency of enzyme synthesis Thea-flavins was explored. The content of polyphenol oxidase in tea samples was determinde, and oxidation product was extracted and analyzed by HPLC. The results showed that the synthesis efficiency varied linearly under gradients concentration Cu₂₊ condition. Optimal value appeared in the condition of n(Cu₂₊)/n(PPO)=0.2, the ethyl acetate layer total thea-flavin content of 45.738%, with a synthesis rate of 35.193%. However, in n(Cu₂₊)/n(PPO) =0.8 condition, tea poly-phenol oxidase oxidation effect was back to the status of n(Cu₂₊)/n(PPO)=0.When n(Cu₂₊)/n(PPO)>0.8, Cu₂₊ appeared on poly-phenols oxidase inhibition. On the other side, conversion rate on catechin, when n(Cu₂₊)/n(PPO)=0.4, the maximum conversion rate was up to 99.05%, after n(Cu₂₊)/n(PPO)>0.4, catechin conversion rate declined. Therefore, the condition of n(Cu₂₊)/nJP3](PPO)=0.2 is the optimal value for tea poly-phenol oxidase enzymatic oxidation synthesizing.