Functional properties of proteins recovered from silver carp (Hypophthalmichthys molitrix) by isoelectric solubilization/precipitation

Isoelectric solubilization/precipitation at acidic and basic pH ranges was applied to whole gutted silver carp (Hypophthalmichthys molitrix) in order to recover muscle proteins. Thermal denaturation (Tonset, Tmax, and ΔH), viscoelasticity (G′), and texture properties (shear stress) of proteins recovered from carp as affected by functional additives (beef plasma protein, potato starch, exogenous transglutaminase, polyphosphate, and titanium dioxide) were determined and compared to Alaska pollock surimi. Proteins recovered from carp showed typical endothermic transitions only when functional additives were used. Similar to endothermic transitions, viscoelasticity in carp proteins increased only when the additives were used. Typical endothermic peaks and viscoelasticity increase were recorded for Alaska pollock surimi. Carp protein-based gels with functional additives had lower (P < 0.05) shear stress than their surimi counterparts, but greater (P < 0.05) or similar (P > 0.05) when compared to surimi gels without functional additives. In addition, generally higher shear stress was measured for carp protein-based gels developed from basic pH treatments than the acidic counterparts. The present study indicates that proteins can be recovered from whole gutted carp using isoelectric solubilization/precipitation. However, if the recovered proteins are used for subsequent development of restructured food products, functional additives should be used.