Effect of CaCl2 and KCl on physiochemical properties of model nutritional beverages based on whey protein stabilized oil-in-water emulsions

Calcium chloride (0 to 10 mM) and potassium chloride (0 to 600 mM) were added into model nutritional beverage emulsions containing 7% (w/w) soybean off droplets and 0.35% (w/w) whey protein isolate (pH 6.7). The particle size, surface charge, viscosity, and creaming stability of the emulsions then were measured. The surface charge decreased with increasing mineral ion concentration. The particle size, viscosity and creaming instability of the emulsions increased appreciably above critical CaCl2 (3 mM) and KCl (200 mM) concentrations because of droplet flocculation. The origin of this effect was attributed to reduction of the electrostatic repulsion between droplets due to electrostatic screening and ion binding. CaCl2 promoted emulsion instability more efficiently than KCl because Ca2+ ions are more effective at reducing electrostatic repulsion than K+ ions.