Separation of grape skins protein from wine sediment by aqueous two-phase systems

Response surface analysis methodology (RSM) was used for optimizing the extraction conditions of grape skins protein from wine sediment in the process of aqueous two-phase systems extraction.Based on single-factor experiments, four independent variables, namely pH, NaCl quality percentage, sample volume added and temperature were selected as affecting factors.The experiments were arranged according to Box-Behnken central composite design.The results showed that the optimum extraction conditions for grape skins protein were as follows:22%PEG600-20% (NH4) 2SO4, pH7.1, NaCl quality percentage 1.2%, sample volume added 2.41mL and extraction temperature was 35.2℃.The predicted grape skins protein extraction yield was 31.66%, while the actual extraction yield was 31.08%.