乌龙茶鲜叶萎凋过程中多酚氧化酶活性的变化

目的]为探讨乌龙茶鲜叶适宜的萎凋条件和萎凋程度。方法]对萎凋过程中关系乌龙茶品质的多酚氧化酶活性的变化进行了研究。结果]鲜叶萎凋6 h,酶活性达到最高水平,随后逐渐下降,且肉桂品种酶活性高于黄旦品种。不同品种酶活性间虽有差异,但趋势基本一致。在温度较低(20℃)、相对湿度较高(90%~95%)的人工条件下萎凋,酶活性高于在室温自然条件下(温度25℃和相对湿度50%~60%)。结论]要达到传统工艺上的摊放要求,宜以低温(20℃)、高湿(相对湿度90%)环境下萎凋为好。

Activity Variations of Polyphenol Oxidas during Withering Process of Oolong Tea

Objective] The research aimed to study the optimal withering conditions and degree of Oolong fresh leaves.Method] Activity variations of polyphenol oxidase(PPO) related to the quality of Oolong tea was investigated during the withering progress.Result] After withering for 6 hours,PPO activity of withered leaves reached the highest level and then decreased gradually.And the activity of PPO from Huangdan was higher than that of Rougui.Regardless of some difference between two examined cultivar,the general variation trend of PPO activity was similar.Under the condition of lower temperature(20 ℃) and higher relative humidity(90%-95%),the enzyme activity in the withered leaves was higher than that at temperature of 20 ℃ and relative humidity of 50%-60%.Conclusion] In order to meet the traditional technical standards,the withering process should be operated under the condition of lower temperature(20 ℃) and higher humidity(about 90%).