Preparation of multiple water-in-oil-in-water emulsions without any added oil-soluble surfactant

摘要

We designed double emulsions without any added oil-soluble surfactant. Simple W-1/O emulsions stabilized solely by fat crystals were first prepared by dispersing the W-1 aqueous phase in a surfactant-less fat phase at a temperature above its melting range, followed by cooling down to trigger bulk fat crystallization. The resulting W-1/O emulsions were arrested systems that were stable against gravitational and colloidal instabilities upon storage. The primary emulsions were in turn dispersed in a highly viscous external aqueous phase containing proteins to obtain W-1/O/W-2 emulsions. We studied the shear and rheological conditions that determine the average oil globule size. The resulting materials had enhanced properties compared to conventional double emulsions including i) very slow passive delivery of the encapsulated species, ii) resistance to osmotic stress, iii) resistance to coalescence, and iv) thermo-responsiveness as the double globules could release the inner droplets' content upon warming.