eng Science and Education Publishing Journal of Food and Nutrition Research 2333-1240 2015-01-06 3 1 34 39 10.12691/jfnr-3-1-6 JFNR2015316 article Xifeng Zhang 1 Fenqin Zhang 1 Guanghong Luo 464690924@qq.com 2 Shenghui Yang 2 Danxia Wang 2 The College of Agriculture and Biotechnology (CAB), Hexi University, Zhangye, P.R. China Kaiyuan Bio-tech Development Center, Hexi University, Zhangye, P.R. China The aim of the current study is to focus on separating the oleanolic acid (OA) from previously prepared aqueous two-phase extraction (ATPE) of grape skins. Several different influential extraction parameters, such as ethanol concentration (v/w), ammonium sulphate concentration (w/w), crude extract concentration (w/w), extraction temperature, and pH, were also investigated. The optimal differential partitioning of OA was achieved in a system (at pH4.0, temperature=25°C)composed of 23% (v/w) ethanol, 18% (w/w) ammonium sulphate, 8% (w/w) crude extract and 41% (w/w) water. The recovery of extracted OA from experiments was determined to be 93.54%. The antioxidant activity of the separated ATPE in relative to VC were, also, investigated in this study at the proper conditions.The ATPE extract showed a relatively high antioxidant ability compared with that of Vitamin C. This proposed extraction technique opens up new possibilities in extraction of other active ingredients in natural plants or biologic samples. http://pubs.sciepub.com/jfnr/3/1/6/jfnr-3-1-6.pdf oleanolic acid Aqueous two-phase extraction (ATPE) Ethanol/ammonium sulphate Antioxidant activity