Recovery and characterization of proteins precipitated from surimi wash-water

Abstract

Abstract The objectives of this study were testing the methodology involved in the recovery of water-soluble proteins from surimi wash-water (SWW) by shifting the pH and organic solvent use, and characterization of the recovered proteins. Water-soluble proteins were recovered from three successive washes in a surimi process; these were: 1.23 ± 0.08, 0.64 ± 0.06 and 0.54 ± 0.05 mg/mL for wash stages I (WS-I), II (WS-II) and III (WS-III), respectively. For WS-I, most of the recovered proteins had a molecular weight (MW) between 23.2 and 71.6 kDa with some traces having less than 23.2 kDa. WS-II and III also had MW between 23.2 and 71.6 kDa; however, at a lower amount. Maximum precipitation from surimi wash-water was obtained at pH 3.5 (66.3 g protein/100 ml SWW). Percentage of precipitation was directly related to temperature. Increasing the organic solvent concentration (10–60 g ethanol/100 g SWW) yielded greater precipitation. The highest precipitation (65.0 g protein/100 mL SWW) was obtained with ethanol concentration of 60 g/100 g SWW. Reaction time for pH shift and organic solvent had little or no significant effect ( p > 0.05) on percentage of precipitation. Minimum solubility of recovered proteins occurred around pH 3.5 and 60 g/100 g of ethanol, an increase in temperature decreased protein solubility.