title: Optimization of microwave-assisted extraction of polyphenols from apple pomace using response surface methodology and HPLC analysis.
abstract: A simple and efficient microwave-assisted extraction of polyphenols from industrial apple pomace was developed and optimized by the maximization of the yield using response surface methodology. A Box-Behnken design was used to monitor the effect of microwave power, extraction time, ethanol concentration and ratio of solvent to raw material (g/mL) on the polyphenols yield. The results showed that the optimal conditions were as follows: microwave power 650.4 W, extraction time 53.7 s, ethanol concentration 62.1% and ratio of solvent to raw material 22.9:1. Validation tests indicated that the actual yield of polyphenols was 62.68±0.35 mg gallic acid equivalents per 100 g dry apple pomace with RSD=0.86% (n=5) under the optimal conditions, which was in good agreement with the predicted yield and higher than those of reflux and ultrasonic-assisted extraction methods. HPLC analysis indicated that the major polyphenols of apple pomace consisted of chlorogenic acid, caffeic acid, syrigin, procyanidin B2, (-)-epicatechin, cinnamic acid, coumaric acid, phlorizin and quercetin, of which procyanidin B2 had the highest content of 219.4 mg/kg.
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, PR China.
authors.forename: Xue-Lian
authors.initials: XL
authors.lastname: Bai
authors.forename: Tian-Li
authors.initials: TL
authors.lastname: Yue
authors.forename: Ya-Hong
authors.initials: YH
authors.lastname: Yuan
authors.forename: Hua-Wei
authors.initials: HW
authors.lastname: Zhang
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005419:Flavonoids / Q000302:isolation & purification*; D027845:Malus / Q000737:chemistry*; D008872:Microwaves; D010636:Phenols / Q000302:isolation & purification*; D059808:Polyphenols; D012015:Reference Standards
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols