Supercritical carbon dioxide extraction of caffeine from Korean green tea

Abstract

Extract caffeine from Korean green tea using supercritical carbon dioxide as an extracting solvent carried out in a 230 mL extractor at extraction temperatures of 313-353 K and pressures of 10-40 MPa with water contents of 15.8-23.8 wt% and flow rate of 5.04-28.08 kg CO2/kg green tea per hour. The result showed that 66% of caffeine was removed under the condition of 323 K, 40 MPa with water contents of 20.8% and a flow rate of 28.08 kg CO2/kg green tea per hour. The experimental results were compared with Goto's mass transfer model in supercritical fluid extraction. It was found to be fit with regression R-2 = 0.95. It was shown that the extraction yields were dependant on the temperature, pressure, water contents, and carbon dioxide flow rate.