Remove Caffeine from Tea by Decompression Sublimation Method

摘要

Caffeine was removed from tea by decompression sublimation method after ultrasonic or microwave treatment for the first time. This paper studied the effect of different atmospheric press, temperature, moisture content, ultrasonic and microwave treatment on the removal of caffeine in tea. Results showed that the decaffeination rate was increased from 6.09% to 7.05% with the decreasing of atmospheric press from-0.02 MPa to-0.06MPa, while further increasing of atmospheric press to-0.08 MPa had almost no influence on it. The decaffeination rate would substantially increased from 7.05% to 24.05% while increased the sublime temperature from 30°C to 70°C, though it would reached to 27.36% when the sublime temperature fixed at 100"C, the high temperature brought on serious carbonization of tea products. The maximal decaffeination rate had great urgent when regulated the moisture of tea from 5% to 10%, while the moisture continue increased to 60%, it had almost no promote. Tea samples were treated by microwave for 2 min and by ultrasonic for 60 min before decompression sublimation, the decaffeination rate would reached to 49.87% and 62.74% respectively, and the main nutrient compounds of tea (such as polyphenols, amino acids) were well remained.