白茶自然萎凋过程中风味形成的动态研究

以福鼎大毫1芽2、3叶鲜叶为原料，以减重率为萎凋阶段划分依据，研究不同阶段在制品的白茶品质风味及生化成分的动态变化。结果表明，在制品的白茶风味在萎凋减重率＞20％时开始产生，40％萎凋减重之后形成较快，萎凋减重率≥60％时，香气、滋味上均表现明显的白茶风味；滋味风味的形成明显滞后于香气；萎凋过程中在制品产生了花香风味，但在70％减重率时，花香风味消失。40％萎凋减重率之后，氨基酸、茶多酚、儿茶素、水浸出物等生化成分变化也较剧烈。因此，在白茶加工过程中通过适当的技术措施，有可能在保持白茶风味不减的条件下，加速萎凋减重率≤40％这一阶段的水分散失速度，调节白茶香气与滋味的形成进程，以缩短萎凋进程，并使成品白茶具有花香品质。

Flavor Formation of White Tea during Natural Withering

Shoots of a bud and two or three leaves from Fuding Dahaocha tea plants (C. sinensis cv. Fuding-dahaocha)were used to study the dynamic changes of the characteristics and chemical composition of the white tea at different withering phases during a work-in-process experimentation. The withering phases were separated based on the weight loss (WL)of the shoots. The results showed that the characteristic flavor of the white tea was not generated until after WL became greater than 20%. At 40% WL,the typical tea flavor began to form rapidly and reached a peak level at 60% WL. During the process,the formation of aroma appeared to proceed that of taste of the tea. The floral fragrance emerged during withering,but dissipated when WL was 70%. Drastic changes on the chemical composition,such as amino acids,polyphenols,catechins,and water extracts,occurred after 40% WL. Consequently,it was believed that appropriate operations could be implemented to accelerate the drying when WL was below 40%,and then,enhance the flavor formation afterward. By doing so,the withering time could be shortened,while the desirable aroma maximally preserved for the white tea as well.