福建主要乌龙茶品种PPO酶活特性的研究

对四种乌龙茶茶树鲜叶的多酚氧化酶(PPO)进行粗提,测定并比较不同品种酶的特性。结果表明:在邻苯二酚与被测酶液的反应体系中,当底物邻苯二酚(C6H6O2)量为0.3~0.9ml时,毛蟹、铁观音、黄旦、肉桂酶活力随底物浓度的增加呈曲线增长,含量太高会产生抑制作用,当底物含量∶酶含量=1.5∶1时,酶活力表现最高;毛蟹、铁观音、黄旦、肉桂酶活力在45~65℃范围内均呈ω型变化趋势,依次在45℃、55℃、65℃时出现高峰。在50~90℃下水浴处理1h,毛蟹、铁观音、黄旦、肉桂酶活力分别丧失34.66%~55.91%,22.68%~50.89%,23.14%~53.57%,31.58%~57.89%;酶活力的适宜pH相对偏碱,在pH8.6时表现为一个活力高峰。相同浓度的五种抑制剂对酶均有一定的抑制效果,其中NaHSO3对酶活力的抑制作用最强,L-半胱氨酸其次,NaCl的抑制效果最差。

Research in Polyphenol Oxidase Activities of Major Oolong Tea Cultivars in Fujian

Crude polyphenol oxidase (PPO) was separately obtained from Maoxie, Tieguanyin, Huangdan, Rougui, and enzymatic properties were examined. The results were as follows: PPO activities increased curvely with the increase of catechol substrate volume if the volume of catechol substrate ranged in 0.3~0.9 ml, and decreased when catechol substrate content was greater than 0.9 ml, in the reaction system; the enzymatic activities were highest when the ratio of catechol substrate content to PPO content was 1.5:1, the optimum temperature for PPO activities were 45℃、55℃、65℃ respectively, under the condition of 50~90℃ hot water treatment for 1 h, the PPO activities of Maoxie, Tieguanyin, Huangdan, Rougui decreased 34.66%~55.91%, 22.68%~50.89%, 23.14%~53.57%, 31.58%~57.89% respectively, PPO could act under alkaline conditions, the best enzymatic activity was detected under the condition of pH8.6; All the five inhibitors showed some degree of inhibition to PPO activities and the most effective inhibitor was NaHSO3, next to which was L-cysteine, while the most ineffective inhibitor was NaCl.