Physical properties of whey protein stabilized emulsions as related to pH and NaCl

Corn oil-in-water emulsions (20 wt%, d(32) approximate to 0.6 mu m) stabilized by 2 wt% whey protein isolate were prepared with a range of pH (3-7) and salt concentrations (0-100 mM NaCl), and particle size, rheology and creaming were measured at 30 degrees C. Appreciable droplet flocculation occurred near the isoelectric point of whey protein (pH 4-6), especially at higher NaCl concentrations. Droplet flocculation increased emulsion viscosity and decreased stability to creaming. Results are related to the influence of environmental conditions on electrostatic and other interactions between droplets.