Both pH value and ionic strength are important for the stability of the emulsions. The interaction between flaxseed gum (FG) and sodium caseinate (CN) was studied by making the state diagram in aqueous solution. And then in emulsions, the possible relationship between FG-CN interaction and the stability of the emulsions were examined by measuring the ζ-potential, droplet size, microstructures, apparent viscosity and surface protein composition. At pH 7, emulsions could be stable for a long time without the addition of NaCl due to FG’s weak gel-like properties. With the increase of NaCl, the electrostatic screening effect made the emulsion ζ-potential decreased as well as their viscosity. But their depletion flocculation was not improved, and NaCl made the samples unstable. At pH 5, emulsions without the addition of NaCl were unstable since the pH was very close to the isoelectric point of CN. NaCl helped the FG adsorb onto the surface of the droplets, and low addition (50 mmol/L) of NaCl improved the stability of the samples.
