低温真空干燥技术对乌龙茶品质影响研究

Study on the effect of low-temperature vacuum drying technology on the quality of Oolong tea

针对乌龙茶在热风干燥过程中香气易于损失、冷冻真空干燥时间长和能耗大的问题,提出采用低温真空干燥技术干燥乌龙茶,即茶叶不经预冻,直接放入真空冷冻机内,控制机内温度在55℃、真空度在100(±30)Pa条件下对其进行干燥;以传统热风干燥、真空冷冻干燥方法为对照,对不同干燥方法乌龙茶中叶绿素等有效成分保留程度、感官品质以及茶叶复水性能等指标进行综合评价。结果表明:低温真空干燥所得的乌龙茶产品外形色泽翠绿、香气鲜灵浓郁、汤色黄绿明亮、滋味醇厚芬芳,综合品质高于用传统的热风干燥和真空冷冻干燥的品质,且能耗和时间均比真空冷冻干燥具有优势,是一种能提高乌龙茶品质的新干燥方法。

The problem that hot air drying of Oolong tea is that the aroma in it is easy to lose, frozen vacuum drying of Oolong tea needs long time and large energy consumption. Research useing low-temperature vacuum drying technology to olry Oolong tea was stadied in this paper. The Oolong tea was put into vacuum refrigerator non-frozen with the temperature at 55℃, and the vacuum at 100（＋30）Pa. Low-temperature vacuum drying, hot air drying traditional method and vacuum freeze drying method were compared to study the impact of low-temperature vacuum drying on active ingredients such as active ingredients preservation degree, sensory quality and rehydration characteristics. The results show that, by comparing the three kinds of drying methods, the quality of Oolong tea presented green color and bright obvious smell and flavour spirit rich, the control of by low-temperature vacuum drying technology, and was better on energy consumption and time. So, the low-temperature vacuum drying technology is a kind of new drying method that can improve the quality of Oolong tea.