减压升华脱除绿茶中的咖啡碱

Removal of Caffeine from Green Tea by Decompression Sublimation

以蒸青绿茶、炒青绿茶为材料,采用减压升华脱除法降低绿茶中的咖啡碱含量。考察了温度、压力、时间条件,以及茶叶种类、含水率和粒度等因素,对咖啡碱减压升华脱除的影响。结果表明,在70℃、-0·02^-0·08MPa条件下,处理14h左右,可使含水率为20%的蒸青绿茶的咖啡碱脱除率达到37%,并基本保持绿茶叶感官品质不变。条形蒸青绿茶在含水率20%的条件下,咖啡碱减压脱除的效果较好。在升华脱除过程中,较高的茶叶水分含量对咖啡碱脱除具有促进作用。减压升华脱除绿茶中咖啡碱的技术条件和设备要求较低,可有效降低传统绿茶中的咖啡碱。

The technique of decompression sublimation was developed to decrease caffeine content of steamed green tea and roasted green tea. The influence of temperature, pressure, time, as well as processing style, moisture and granularity of green tea on decaffeination was investigated. The results showed that 37 % of caffeine was removed from the steamed green tea with moisture of 20 % but the sensory quality was kept under the pressure of - 0.02～ - 0.08 MPa at 70 ℃ for 14 h. The decaffeination rate was increased with higher moisture content of green tea. Caffeine can be effectively removed from green tea with decompression sublimation in the low level of engineering factor and the equipment request.