遮荫对夏暑乌龙茶主要内含化学成分及品质的影响

Effects of shading on quality and chemical components of Oolong tea in summer

探讨了黄旦、铁观音和本山茶园覆盖遮荫对茶叶品质的影响。结果表明：遮荫可以显著提高夏、暑乌龙茶的品质，明显降低酚／氨比值．优化儿茶素组分和香气组分。遮荫度为30％、45％和60％3种处理的夏、暑乌龙茶品质得分均极显著高于不遮荫对照处理。而遮荫处理间的差异不显著；与对照相比，遮荫后夏茶乌龙茶鲜叶的茶多酚总量、儿茶素和EGC的含量分别下降了2．59％～12．40％、2．14％～13．63％、11．17％～29．47％。暑茶乌龙茶鲜叶茶多酚总量、儿茶素和EGC含量分别下降了8．68％～11．05％、3．09％～10．61％、12．76％～24．23％；儿茶素品质指数分别提高了54．13～84．87和157～682；夏茶氨基酸含量提高了13．52％～60．00％．其中茶氨酸、苏氨酸和天门冬氨酸的总量增加了7．57％～19．12％；夏、暑乌龙茶的香气种类和香精油总量分别增加了25～40种和21．20％～38．85％．香气组分明显得以优化。

Three Oolong tea cultivates, including Huangdan, Tieguangying and Benshan, were shaded in summer to probe its effect on tea quality. The results showed that shading in Oolong tea garden during summer could markedly improve the tea quality, decrease the ratio of polyphenol and amino acid, optimize the components of the catechin and fragrance. Under the shading degree of 30%, 45 % and 60%, the scored of tea quality was much higher than that of control which without shading in summer, and the differences between the treatments were indistinctive. Compared with the control, shading tea garden in summer and hot weather days. the contents of tea polyphenol decreased 2.59%-12.40% and 8.62%-11.05%, the contents of catechin decreased 2.14%-13. 63% and 3.09%- 10. 61%, and that of EGCG decreased 11.17 %- 29.47 %, respectively. The indexes of catechin quality increased 54. 13-84. 87 and 167-682. The contents of amino acid increased 13. 52%-60%, among which the total contents of theanine, threonine and asparagic acid increased 7.57 %- 19.12 %. The fragrance kinds increased by 25-40, and the total contents of the essential oil increased 21.20%-38.85 %, The components of fragrance were optimized.