Effects of the Density Difference between Water and Oil on Stabilization of Powdered Oil-in-Water Emulsions

A powdered oil-in-water (o/w) emulsion is a dispersed system in which the continuous phase of a particle-stabilized o/w emulsion is dispersed in air by encapsulating the water globules with hydrophobic particles. During their preparation, oil droplets in water globules are forced to move because of high-shear mixing, leading to creaming of the oil droplets and possible wetting of the hydrophobic particles with the oil droplets, which induces destabilization. To prepare powdered o/w emulsions efficiently, the extent of creaming of the oil droplets has to be suppressed. We describe how to achieve this by mixing two oils of different densities and preparing powdered o/w emulsions from oil mixtures exhibiting a decreasing density difference with water. As the extent of creaming is reduced, enhanced stabilization of the powdered emulsions occurs.