title: Optimization of ultrasonic extraction of phenolic antioxidants from green tea using response surface methodology.
abstract: Response surface methodology (RSM) has been used to optimize the extraction conditions of antioxidants with relatively low caffeine content from green tea by using ultrasonic extraction. The predicted optimal conditions for the highest antioxidant activity and minimum caffeine level were found at 19.7% ethanol, 26.4 min extraction time, and 24.0 ° C extraction temperature. In the predicted optimal conditions, the experimental values were very close to the predicted values. Moreover, the ratio of (EGCg + ECg)/EGC was identified a major factor contributing to the antioxidant activity of green tea extracts. In this study, ultrasonic extraction showed that the ethanol concentration and extraction time used for antioxidant extraction could be remarkably reduced without a decrease in antioxidant activity compared to the conventional extraction conditions.
authors.affiliation: Korea Food Research Institute, Seongnam, Kyonggi 463-746, Korea. radog@kfri.re.kr.
authors.forename: Lan-Sook
authors.initials: LS
authors.lastname: Lee
authors.forename: Namhyouck
authors.initials: N
authors.lastname: Lee
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Chang-Ho
authors.initials: CH
authors.lastname: Lee
authors.forename: Sang Pil
authors.initials: SP
authors.lastname: Hong
authors.forename: Yeo-Won
authors.initials: YW
authors.lastname: Jeon
authors.forename: Young-Eon
authors.initials: YE
authors.lastname: Kim
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002110:Caffeine / Q000737:chemistry; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D013662:Tea / Q000737:chemistry*; D014465:Ultrasonics
chemical_list: D000975:Antioxidants; D010636:Phenols; D010936:Plant Extracts; D013662:Tea; C417940:gallocatechin gallate; D002110:Caffeine; D002392:Catechin; C045651:epigallocatechin gallate; C057580:gallocatechol