title: Supercritical carbon dioxide extraction of flavonoids from pomelo (Citrus grandis (L.) Osbeck) peel and their antioxidant activity.
abstract: Supercritical carbon dioxide (SC-CO(2)) extraction of flavonoids from pomelo (Citrus grandis (L.) Osbeck) peel and their antioxidant activity were investigated. Box-Behnken design combined with response surface methodology was employed  to maximize the extraction yield of flavonoids. Correlation analysis of the mathematical-regression model indicated that a quadratic polynomial model could be used to optimize the SC-CO(2) extraction of flavonoids. The optimal conditions for obtaining  the highest extraction yield of flavonoids from pomelo peel were a temperature of 80 &deg;C,  a pressure of 39 MPa and a static extraction time of 49 min in the presence of 85%  ethanol as modifier. Under these conditions, the experimental yield was 2.37%, which matched positively with the value predicted by the model. Furthermore, flavonoids  obtained by SC-CO(2) extraction showed a higher scavenging activity on hydroxyl, 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2&apos;-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radicals than those obtained by conventional solvent extraction (CSE). Therefore, SC-CO(2) extraction can be considered as a suitable technique for the obtainment of flavonoids from pomelo peel.
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology,  Hangzhou 310032, China. ruqiaomei@zjut.edu.cn.
authors.forename: Jin-Zhe
authors.initials: JZ
authors.lastname: He
authors.forename: Ping
authors.initials: P
authors.lastname: Shao
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
authors.forename: Qiao-Mei
authors.initials: QM
authors.lastname: Ru
mesh_terms: D000704:Analysis of Variance; D000975:Antioxidants / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D025924:Chromatography, Supercritical Fluid; D002957:Citrus / Q000737:chemistry* / Q000378:metabolism; D000431:Ethanol / Q000737:chemistry; D005419:Flavonoids / Q000737:chemistry*; D010084:Oxidation-Reduction; D010936:Plant Extracts / Q000737:chemistry; D011312:Pressure; D013696:Temperature
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; D002245:Carbon Dioxide; D000431:Ethanol