Oxidative enzymes, polyphenol oxidase (PPO) and peroxidase (POD), were extracted from tea leaves and their activities were assessed. The Taguchi approach was used for the design, optimization, and statistical analysis of PPO and POD extraction. It was found that PPO and POD have the highest activity at an extraction temperature of 50 °C, at pH = 9 and 5 for PPO and POD, respectively, a buffer solution concentration of 0.05 M, a buffer solution/tea leaves ratio of 3, a contact time of 2 min, and in the presence of 6 % polyvinylpyrrolidone and 5 % Tween® 80. The highest activities were 0.380 and 0.022 U mL⁻¹ for PPO and POD, respectively. Furthermore, PPO was completely inactivated after 30 min at 40 and 60 °C. In contrast, POD lost only 40 % of its activity after 30 min at 40 and 60 °C.

中文翻译：

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绿茶叶中氧化酶的提取及提取条件的优化

从茶叶中提取氧化酶，多酚氧化酶（PPO）和过氧化物酶（POD），并评估其活性。Taguchi方法用于PPO和POD提取的设计，优化和统计分析。结果发现，PPO和POD在50℃的提取温度，pH = 9和5时对PPO和POD的活性最高，缓冲液浓度为0.05 M，缓冲液/茶叶的比例为3 ，接触时间为2分钟，在6％聚乙烯吡咯烷酮和5％Tween®80存在下。PPO和POD的最高活性分别为0.380和0.022 U mL ^-1。此外，在40和60°C下30分钟后，PPO完全失活。相反，POD在40和60°C下放置30分钟后仅损失其活性的40％。