Separation of catechins from green tea using carbon dioxide extraction

This study presents a novel packed-column extractor coupled with an absorption system to improve the quality of green tea essential oils, extracted by using high-pressure carbon dioxide. The effects of various co-solvents on the extract are also examined. In addition, gravimetric measurement and HPLC chromatographic analyses individually determine the amount of essential oil and the concentration of four major catechins. Results show that the mean contents in the extract are 4.4-fold higher by addition of 95% ethanol than by addition of water. The ratio of polyphenols to caffeine is highest in the Soxhlet ethanol extraction.