Decaffeination of green tea by supercritical carbon dioxide

Abstract

Effects of cosolvent, tea particle size, extraction temperature and time on the removal of caffeine and catechins from green tea using supercritical carbon dioxide method were investigated. It showed that ethanol was optimal cosolvent. Water and 50% aqueous ethanol were not suitable for cosolvents because a large percentage of catechins were removed. Based on the orthogonal array design tests, optimal protocol for green tea decaffeination was screened as 10 g of 0.2 - 0.6 mm particle size green tea was extracted using 15 ml ethanol cosolvent at 80°C for 2 h when flow rate and pressure of SC- CO2 were at 1.5 L min-1 and 300 bars, during which 70.2% caffeine and 6.2% catechins were removed, respectively.   Key words: Decaffeinated tea, supercritical fluid extraction, cosolvent, particle size, temperature, caffeine, catechins.