Interfacial adsorption and shear flow properties of gum arabic-sodium caseinate mixtures

This work discusses rheological and physicochemical properties of sodium caseinate and gum arabic, in aqueous media (25 °C). All the systems showed low viscosity values and Newtonian behaviour in the shear rate range studied. From particle size distribution, a limited thermodynamic compatibility was observed since hydrocolloids mixtures showed particles size between the values from the systems alone. Interfacial tension measurements at equilibrium at the air-water interface, revealed that the binding affinity of arabic to the air water interface is very low compared to that of caseinate. The adsorption critical concentration could be deduced as a function of aqueous solutions composition. In competitive adsorption experiments involving simultaneous adsorption of the hydrocolloids from a bulk mixture, sodium caseinate displaced gum arabic from the interface at both polysaccharide concentrations, changing the adsorption critical concentration.