Stability and microstructure of food-grade double emulsions

Abstract

Purpose: Stable, food-grade water-in-oil-in-water double emulsions (DEs) were designed for possible controlled release applications in foods. Methodology: The primary water-in-oil emulsion prepared with water, canola oil, polyglycerol polyricinoleate (PgPr), sodium chloride (NaCl) and gelatin was sta- ble for months. DEs were developed by dispersing the primary emulsion into a continuous aqueous phase containing different hydrophilic emulsifiers and stabilizers, such as sodium caseinate, gum arabic, polysorbate 80, sodium algi- nate, and poloxamer 188. Combinations of polysorbate 80 with polysaccha- rides (gum arabic or sodium alginate) were also investigated. Findings: Stability of DEs was observed macroscopically via sedimentation tests whereas microstructure were examined using light microscopy. Polysorbate 80 was the most suitable hydrophilic emulsifier for obtaining stable DEs. A hyper- tonic internal aqueous phase resulted in increased emulsion stability. Value: Given their long-term kinetic stability, such DEs may potentially be used as controlled release matrices or texture modifiers in foods.