Effects of processing parameters on the caffeine extraction yield during decaffeination of black tea using pilot-scale supercritical carbon dioxide extraction technique.

In this pilot-scale study supercritical carbon dioxide (SCCO2) extraction technique was used for decaffeination of black tea. Pressure (250, 375, 500 bar), extraction time (60, 180, 300 min), temperature (55, 62.5, 70 °C), CO2 flow rate (1, 2, 3 L/min) and modifier quantity (0, 2.5, 5 mol%) were selected as extraction parameters. Three-level and five-factor response surface methodology experimental design with a Box-Behnken type was employed to generate 46 different processing conditions. 100% of caffeine from black tea was removed under two different extraction conditions; one of which was consist of 375 bar pressure, 62.5 °C temperature, 300 min extraction time, 2 L/min CO2 flow rate and 5 mol% modifier concentration and the other was composed of same temperature, pressure and extraction time conditions with 3 L/min CO2 flow rate and 2.5 mol% modifier concentration. Results showed that extraction time, pressure, CO2 flow rate and modifier quantity had great impact on decaffeination yield.