Abstract: 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 0.3~0.9βml, and decreased when catechol substrate content was greater than 0.9βml, 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 1βh, 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.

Key words: Oolong tea, fresh tea, polyphenol oxidase