Effects of Mixing Ratio and pH on the Electrostatic Interactions of Hydrolyzed Alaska Pollock Protein and κ-Carrageenan.

In order to widen the application of Alaska Pollock salt-soluble protein and improve the properties of κ-carrageenan (KC), we evaluated whether the electrostatic interaction between KC and hydrolyzed protein (HP) improved the solubility of salt-soluble proteins and assessed acid hydrolysis-induced changes in the viscosity of KC. Moreover, we determined the effects of pH, KC, and HP mixing weight ratio (R, from 1:8 to 8:1) on the properties of mixtures. ζ-Potential results demonstrated that there were electrostatic interactions between KC and HP. Results of solution transmission and precipitation diagram analysis demonstrated that increasing the ratio of KC in KC-HP mixtures expanded the pH range of HP water solubility and prevented HP from precipitating, even at pH values around the pI. The highest viscosity of the solution measured by rheology analysis occurred at pH 3.5, and the ratio of KC:HP (R) was 1:1. These findings suggested that Alaska Pollock protein could be modified appropriately for use in acidic solutions and semisolid foods; moreover, KC-HPs have a potential application as thickeners in acid condition.

PRACTICAL APPLICATION: These findings suggested that Alaska Pollock protein could be modified appropriately for use in acidic solutions and semisolid foods and that KC-HP may have applications as a new acid thickener.