炒青绿茶热解吸特性

Property of Heat Desorption of Roasted Green Tea

对炒青绿茶杀青和炒干过程的热特性进行了跟踪测量。结果表明，杀青过程的热解吸具有等速特性；炒干过程的热解吸则呈现恒率失水和降率失水的双重特性。鲜叶的嫩度不同，其热解吸特性也不尽相同，杀青过程中一级鲜叶的热解吸速率大于三级叶，一级和三级鲜叶杀青前期（２ｍｉｎ），茶叶吸热量分别占总吸热量的３８％和４２％；炒干过程中，一级原料解吸至１５％含水率左右时，开始降率解吸，而三级原料的降率解吸含水率起始点则要提前至２５％—３０％含水率时。温度和解吸速度对炒青品质的形成起着推动作用。

The thermal property of the in processing leaves was investigated by continuously measuring the temperature and the moisture content of the in processing leaves during both the enzyme inhibiting and the roasting procedures.The moisture desorption of the in processing leaves possessed an equal rate during the whole enzyme inhibiting process and in the early stage of the roasting process,but a reducing rate in the late stage of the roasting process.The rate of moisture desorption varied with the tenderness of the fresh leaves ,and the rate of the first grade leaves was greater than that of the third grade leaves.In the early stage (2 min) of the enzyme inhibiting process,the absorbed heat by the in processng leaves occupied 38% (leaves of grade one)/42%(leaves of grade three) of the total absorbed heat during the whole enzyme inhibiting process.In the roasting process,the reducing rate desorption began when the moisture content of the in processing leaves (of grade three) dropped to 25%—35%,but for the grade one leaves,the equal rate desorption continued until the moisture content of the in processing leaves dropped to 15%.The heating temperature and the moisture desorption rate effectively promoted the quality formation of the roasted green tea ,and the desorption rate was restrained by the surrounding temperature and relative humidity.