Protein-stabilized water-in-oil-in-water emulsions

Abstract Multiple water-in-oil-in-water (W/0/WJ emulsions are inherently less stable than ordinary oil-in-water (0/W) emulsions. In addition to the usual processes of creaming, flocculation and coalescence of the outer (oil) droplets, there is-with a multiple emulsion-the possibility of destabilization due to swelling and coalescence of the inner droplets, leading to rupture of the duplex film between inner and outer aqueous phases. These tendencies are exacerbated by the presence of both hydrophilic and hydrophobic emulsifiers which may migrate between inner and outer oil-water interfaces with consequent detrimental effects for emulsion stability. The use of a two-stage process to make a W/0/W emulsion that is stable to creaming requires extremely vigorous emulsification conditions during the second stage in order to produce droplets no bigger than a few micrometres in diameter. These vigorous conditions have the undesirable potential for disrupting the primary water-in-oil (W/0) emulsion droplets, thereby reducing the yield of multiple emulsion.