A comparison of heat-induced gel strengths of bovine plasma and egg albumen proteins.

Abstract

The heat-induced gel strength in suspensions of two types of plasma protein isolates and egg albumen were compared to investigate the use of bovine blood plasma in food systems as a replacement for egg albumen and other proteins. A viscosity index, based on a counter-flow back-extrusion model, was used to measure gel strength. The optimum pH for gel formation was 7.0 for phosphated and nonphosphated plasma protein suspensions and 9.0 for egg albumen. The protein gel strengths were compared at 8% protein concentrations and at their respective pH optima. The gel strength of heated bovine plasma protein suspensions was greater (P < .01) than that of egg albumen, indicating that blood plasma exhibited a binding ability superior to that of egg albumen. The addition of controlled low levels of sodium and calcium increased (P < .05) the binding ability of both plasma protein isolates, while egg albumen showed no changes (P > .05). Greater concentrations substantially decreased (P < .01) the gel strength in both types of heated plasma protein suspensions and egg albumen, revealing that all three protein types exhibited an ionic strength dependency.