Functional Properties of Water-Soluble Proteins from Silver Carp (Hypophthalmichthys molitrix) at Different pHs

摘要

Water-soluble proteins (WSP) from silver carp muscle are currently underutilized in China and are discarded into waste streams in surimi processing. In order to utilize WSP resources efficiently, this work investigated the effect of pH on the functional properties of WSP. With an increase in pH, the solubility decreased and then increased; the lowest solubility was observed at pH 4.0. Also, heat-stability, emulsifying activity index (EAI), and foamability decreased and then increased with increasing pH; the lowest values were shown at pH 5.0. The better heat-stability, EAI, and foamability were obtained at pH 3.0. An increase in total sulfhydryl content was observed when the pH was 3.0-5.0, and a decrease was obtained at pH 5.0-9.0. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of WSP treated at various pHs showed that molecular weights of the main WSP ranged from 30 to 97 kDa. The WSP was recovered by adjusting the pH to 4.0-5.0, and the functional properties of WSP were greatly affected by pH value.