Edible high internal phase Pickering emulsion with double-emulsion morphology

Food-grade high internal phase Pickering emulsions (HIPPEs) unify the stability of Pickering emulsions and the advantages of detergent-based high internal phase emulsions (HIPEs), making them attractive as nutritional products. However, as oral delivery systems, HIPPEs are usually prepared in the form of o/w emulsions, which are suitable mainly for oleophilic active ingredients and may suffer from leakage during gastric digestion. To better protect and deliver hydrophilic cargo molecules, we developed a HIPPE-based w/o/w double emulsion system. Zein nanoparticles and soybean lecithin are found to have a synergistic effect in stabilization — using both natural emulsifiers together results in the formation of w/o/w double emulsions with improved stability, which is further confirmed by the interfacial tension and rheology of zein- and/or lecithin-laden oil-water interfaces. A combination of zein nanoparticles and lecithin achieves the fastest interfacial tension decrease, indicating an improved interfacial activity. Besides, lecithin contributes to the strong surface elasticity of the interfacial films, which makes the formed emulsions even stabler. Simulated digestion experiments suggest that the inner aqueous droplets can be strongly protected from gastric fluids. This edible HIPPE with double emulsion morphology provides new ideas for designing healthy foods for nutrients delivery.