The effects of casein and whey proteins on the rheological properties of calcium-induced skim milk gels

Abstract

This study aimed to determine the interactive effects of casein, whey proteins and calcium ions on the rheological properties of calcium-induced skim milk gels. Skim milk blends with different casein to whey protein ratios (95:5, 93:7, 90:10, 85:15 and 80:20) were either not preheated or preheated at 90 °C for 10 min, and calcium chloride was added at 0–40 mmol L−1. Results suggested that the final gel strength (G′) was dependent on the concentration of added calcium chloride, ratio of casein to whey proteins, and whether the whey proteins were denatured by preheat treatment. Denatured whey proteins in preheated skim milk blends appeared to lead to two competing effects on the gel strength: reduced gel strength due to competition with casein micelles for calcium ion binding; and enhanced gel strength by participating in the gel structure through aggregation via calcium-bridging, hydrophobic interactions, and disulphide bonding.