Phenolic extraction from grape (Vitis vinifera) seed via enzyme and microwave co-assisted salting-out extraction

Abstract The aim of this study was to develop an effective method for extracting total phenolic (TP) from grape seed using enzyme and microwave co-assisted salting-out extraction (EMASOE). The significant factors affecting TP yield were screened by Plackett-Burman design and then optimized by Box-Behnken design. Under optimum extraction conditions of 25% (w/w) ethanol/20% (w/w) ammonium sulfate, pectinase amount 540 U/g, enzymatic pH 4.5, microwave power 180 W, the maximum extraction yield of TP was 125.32 mg/g. Significant differences were found in the monomer phenolic compounds by different methods. Ten kinds of monomer phenolic compounds were analyzed by high pressure liquid chromatography (HPLC), only four were identified by Soxhlet extraction (SE), and eight by EMASOE. Moreover, the TP by this method possessed higher content and better antioxidant activities. Therefore, EMASOE could be used as an effective method to extract phenolics from natural plants.