The effect of organic acids on gelation characteristics of protein gels made from silver carp (Hypophthalmichthys molitrix) protein recovered by isoelectric solubilization and precipitation

Abstract

Isoelectric solubilization and precipitation (ISP), a protein recovery process, was applied to ground, headed and gutted silver carp (Hypophthalmichthys molitrix) at both acidic and basic solubilization pH values using either glacial acetic acid (AA) or a combination of formic and lactic acid (F&L). Functional and textural properties of protein pastes and cooked gels made from recovered protein with standard additives were examined. Thermal denaturation and viscoelasticity of protein pastes were measured; pastes presented with endothermic reactions typical of non-denatured protein. Protein solubilized using AA and F&L resulted in endothermic properties similar to Alaska Pollock surimi. ISP-recovered protein presented with rheological characteristics typical of myofibrillar proteins from other marine protein sources. Viscoelastic properties of proteins solubilized at basic conditions using F&L had a high elastic modulus (G′), which is an indication of good gelation and gel quality. Shear stress on cooked gels was highest (p < 0.05) in gels made from protein solubilized at pH 11.5 using AA. Protein recovered by ISP processing retained their functionality and gels made from the protein were similar to surimi; therefore, potential exists for its use as a high quality protein source.