Thermodynamic incompatibility of whey proteins with polysaccharides in aqueous media

Phase diagrams of aqueous whey protein (WP) and polysaccharide (PS) mixtures, including carboxymethylcellulose (CMC), k-carrageenan (C) and locust bean gum (LG) are presented in this paper at pH from 5.0 to 7.0 with 0.1 to 0.5 M NaCl. Thermodynamic incompatibility of WP-CMC, WP-LG and WP-C systems increased as pH was close to the isoelectric point of WP (pI=5.2). Increasing salt concentration (0.1 to 0.5 M) increased the incompatibility of WP-LG and WP-CMC systems. However, the effect of NaCl on thermodynamic incompatibility of WP-C was the opposite, i.e. increasing salt concentration decreased the thermodynamic incompatibility of the system. The type of the polysaccharides was the critical factor, which affected the compatibility of WP-PS systems. The thermodynamic compatibility of WP-PS systems decreased in the following order: locust gum ≯ carboxymethylcellulose ≯ k-carrageenan