Microwave‐assisted aqueous two‐phase extraction of phenolics from grape (Vitis vinifera) seed

Abstract

AbstractBACKGROUNDThe wine making process produces a large quantity of grape marc, which includes grape seeds, skins, and stems. These byproducts comprise approximately 20% of the harvested grapes. Aqueous two‐phase extraction (ATPE) composed of short‐chain alcohol, inorganic salt, and water is a novel approach used to separate active constituents from fermentation broth or natural plant. A microwave‐assisted aqueous two‐phase extraction (MAATPE) method was used to obtain phenolic compounds from grape seeds. The partitioning behavior of the phenolic compounds in the MAATPE system was assessed.RESULTSPhenolic compounds were extracted into the top acetone‐rich phase at 32% (w/w) acetone/16% (w/w) ammonium citrate. The maximum yield of total phenolics, flavonoid, and proanthocyanidin were 82.7, 52.6, and 30.7 mg g−1, respectively. The corresponding recovery rates were 97.1%, 97.9%, and 99.3%. The antioxidant activity of seed extracts was determined by 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate) (ABTS) radical‐scavenging ability (IC50). No significant correlation was found between free radical scavenging capacity and TP content.CONCLUSIONMAATPE required lower solvent concentration and less treatment time to extract high amounts of phenolics from grape seeds compared with the other methods. MAATPE has the potential for the extraction, clarification, and concentration of target products using a single step. © 2013 Society of Chemical Industry