Stabilization of multilayered emulsions by sodium caseinate and κ-carrageenan

The influence of the kappa-carrageenan concentration and pH on the properties of oil-in-water multilayered emulsions was studied. Multilayered emulsions were prepared by the mixture of a primary emulsion stabilized by 0.5% (w/v) sodium caseinate (Na-CN) with kappa-carrageenan solutions with different concentrations (0.05-1% w/v). The emulsions were evaluated at pH 7 and 3.5. At pH 7, there was little adsorption of kappa-carrageenan onto the droplet surface and a depletion flocculation was observed when the polysaccharide concentration exceeded 0.5% (w/v). At pH 3.5, a mixed kappa-carrageenan-Na-CN second layer was formed around the protein-covered droplets and the emulsions showed bridging flocculation at lower polysaccharide concentrations (0.05-0.25% w/v). Stable emulsions could be formed with the highest kappa-carrageenan concentration (1% w/v) at both pH values (7.0 and 3.5). Thus, stable emulsions were successfully produced using protein-polysaccharide interfacial complexes, and the oil droplet diameter, zeta potential and rheological properties of these emulsions were not affected by changes in the pH. (C) 2012 Elsevier Ltd. All rights reserved.