Optimization of the extraction condition for grape seeds procyanidins in aqueous two-phase systems by response surface analysis

An aqueous two-phase system composed of 20% PEG4000 and 10% ( NH 4) 2 SO 4 was used to extract procyanidins from grape seeds.The effect of crude extract concentration, pH and NaCl on the extraction efficiency of procyanidins were explored by single factor experiments and response surface analysis test. The optimal aqueous two-phase extraction conditions were crude extract mass concentration 17.2%, pH4.8 and NaCl 0.7%. Under the optimal extraction conditions, procyanidins from grape seeds was mainly distributed in the upper phase with a extraction ratio of 96.66%.