Abstract:

Green tea polyphenols (TPs) were extracted by hot water reflux extraction, combination of cellulase hydrolysis and ultrasound-assisted extraction or each of them and extraction with room temperature water, respectively, and the resultant products were measured for their physico-chemical properties. The results showed that the extraction efficiency and product purity resulting from hot water reflux extraction at 90 ℃ were higher than those resulting from other 4 methods, but the product obtained had lower hydroxyl free radical scavenging activity than that obtained at lower reflux temperatures. Ultrasoundassisted extraction at room temperature exhibited better extraction efficiency and product purity, and the hydroxyl free radical scavenging activity of the product obtained was higher than that of the products obtained by other 4 methods. Combination of ultrasound-assisted extraction and cellulase hydrolysis gave better extraction efficiency; however, the purity and hydroxyl free radical scavenging activity of the product obtained were both lower than those of the product obtain by ultrasound-assisted extraction alone.

Key words: tea polyphenols, extraction, hydroxyl free radical scavenging activity