Microwave extraction of catechins from green tea using ionic liquid.

Green tea polyphenols (GTP) are known for their antioxidant properties, which are
contributed by polyphenols. Therefore efficient extraction methods for these polyphenols are
required. The effects of various parameters on the extraction of green tea polyphenols were
studied using Ionic Liquid. Aqueous Ionic liquid solvent was used for microwave extraction
of catechins from green tea. The extraction parameters taken were; temperatures (50ºC, 60ºC,
70ºC and 80ºC) ,wattage (200W, 400W, 600W and 800W), time of extraction() 2,4 and 6
minutes and IL concentration (0.025M, 0.05M and 0.1M). The extracts were desolvatized to
obtain extracts. Assays were conducted for these extracts to measure their antioxidant
activities. Catechins were quantitatively analysed using HPLC. Extracts at optimised
condition (i.e., 80ºC, 0.1M, 800W, 4 min) showed high flavonoid content and better radical
scavenging activity. Quantitative analysis of the catechins( EGC, EGCG, ECG and CG) by
HPLC showed maximum catechin concentration in IL extracts at 80°C. IL extracts showed
better yield, high antioxidant properties and high concentration of green tea catechins (84.12g
%).