W1/O/W2 double emulsions stabilised by fat crystals--formulation, stability and salt release

Water/oil (W(1)/O) emulsions containing fat crystals have been incorporated into an aqueous phase containing 1% na-caseinate as emulsifier to create stable water/oil/water (W(1)/O/W(2)) double emulsions. The W(1)/O primary emulsion was stabilised exclusively with monoglyceride and triglyceride crystal "shells", and contained 30% W(1) aqueous phase as well as KCl. The stability of the double emulsions was monitored over the course of 6 weeks. It was found that, providing some salt or sugar were present in the W(2) aqueous phase, emulsions retained their double structure--although coalescence between double emulsion globules occurred and creaming was observed. KCl encapsulated in the W(1) phase of the primary emulsion was only slowly released to the W(2) continuous aqueous phase: 20% within 6 weeks. This release is due to the damage caused to the fat crystal shells during the secondary emulsification step used to create the double emulsion structure.