茶鲜叶在不同季节及绿茶加工贮藏过程中糖苷类香气前体含量变化研究

选择了槠叶种鲜叶为茶叶原料 ,研究了茶叶糖苷类香气前体在不同季节和绿茶加工过程中的消长规律。研究结果表明 ,槠叶种鲜叶中存在以顺 3 己烯醇、芳樟醇及其氧化物、水杨酸甲酯、香叶醇、苯乙醇、苯甲醇等为苷元的糖苷类香气前体。不同季节 ,茶叶糖苷类香气前体在组成和含量上差别较大。单萜烯醇糖苷特别是香叶醇糖苷在春茶中的含量很高 ;秋茶中以芳香族醇、酯、脂肪族醇为苷元的糖苷含量显著增加 ,而单萜烯醇糖苷含量降低 ;夏茶中水杨酸甲酯、苯甲醇糖苷含量处于低水平 ,但苯乙醇糖苷含量较高。从春季到秋季 ,顺 3 己烯醇和水杨酸甲酯糖苷的含量逐渐提高 ,而芳樟醇和香叶醇糖苷的含量却逐步减少。茶鲜叶摊放 2h后 ,糖苷类香气前体的总量提高 ,并在绿茶加工的后续阶段逐步降低 ,特别是在干燥阶段。在成品绿茶中仍保留约 77%的糖苷类香气前体 ,这为绿茶香气品质的进一步改善留下了广阔的空间。

Studies on the Content of Glycosidic Tea Aroma Precursors in Leaves of Zhuye during Different Seasons, Green Tea Processing and Storage

The quantity, quality of glycosidic aroma precursors during green tea manufacture were studied with the leaves of Camellia sinensis var. Sinensis cv. Zhuye ( cultivated for green and black tea ) as the materials. The glycosidic aroma precursors in leaves of Zhuye are mainly consisted of glycosides of cis 3 hexenol, linalool and its oxides, methyl salicylate, geraniol, benzyl alcohol and phenylethanol. The amounts and components of glycosidic aroma precursors in tea leaves varied obviously with the change of season. The amount of aroma precursors was richer in leaves of spring and autumn than that of summer. Interestingly, glycosides of monoterpene alcohols were abundant in spring leaves, especially geraniol. While glycosides of aryl alcohols were rich in autumn. During withering, the content of glycosidic aroma precursors increased greatly than that in fresh leaves, while it declined in the later green tea manufacturing process, especially in dry process. About 77% of the glycosidic aroma precursors in fresh tea leaves remained in the final green tea product, which was perceived a potential source of additional green tea aroma.