W/O/W‐type Multiple Emulsions With a View to Possible Food Applications1

W/O/W‐type multiple emulsions have potential applications for the formulation and processing of foods, as each dispersed globule in this type of emulsion consists of single or multiple aqueous compartments separated from the aqueous suspending fluid by a layer of the oil phase components. Three different methods can be applied to prepare W/O/W emulsions, such as mechanical agitation, the phase inversion technique and a two‐stage emulsification. The oil layer in the W/O/W emulsions appears to thin immediately after the preparation, and water permeates through the narrow oil layer under the osmotic pressure gradient between the two aqueous phases. Therefore, it is believed that the thin oil layer may contain the hydrophobic emulsifier in a lamella structure. Addition of electrolytes to the aqueous phase causes instability of the W/O/W‐type dispersion due to rupture of the thin oil layer, or aggregation formation amongst the dispersed globules. A systematic study of the W/O/W emulsion stability is desirable in view of possible applications of this type of emulsion in foods.