Caffeine extraction from green tea using supercritical CO₂

Abstract

It has been discoverd that green tea contains various components with anti-oxidant and anticarcinogenic properties. Green tea usually contains caffeine(1-5%) and catdchin(5-27%). Caffeine typically is used as a stimulant which could affect central nervous system and is beneficial towards the portions of the brain that affect mental alertness. The extraction of caffeine from green tea using supercritical carbon dioxide is investigated in this paper. The operating pressure in the extraction was varied from 10 to 40MPa, the temperature was varied form 40 to 60oC, and solvent flow rate was varied from 17.4 to 0.37mL/min. Caffeine extraction wields using supercritical carbon dioxide were found to be approximatel 50% at 40MPa, 50oC and 0.37mL/min solvent flow rate. Theoretical model proposed by Goto et al, was compared with the experimental results an dit was found to be fit with the data well. the theoretical model shows that the extraction yield depends on the solvent flow rate, temperature and pressure.