Influence of emulsifier type on freeze-thaw stability of hydrogenated palm oil-in-water emulsions

The influence of emulsifier type (Tween 20, whey protein isolate, casein) on the physical properties of 20 wt% hydrogenated palm oil-in-water emulsions after crystallization of (i) the oil phase only or (ii) both the oil and water phases has been examined. Emulsion stability was assessed by differential scanning calorimetry measurements of fat destabilization after cool-heat cycles, and by measurements of mean particle size, oiling off, and gravitational separation after isothermal storage (- 20 to 37 degreesC. Tween 20-stabilized emulsions showed appreciable fat destabilization at temperatures where the oil phase was partially crystalline, which was attributed to partial coalescence. Protein- stabilized emulsions were stable under these conditions, which was mainly attributed to the relatively thick interfacial membranes surrounding the droplets. When both oil and water phases crystallized, there was complete destabilization of Tween 20- and casein-stabilized emulsions, and extensive destabilization of whey protein-stabilized emulsions, which was attributed to ice crystallization. The results of this study could facilitate the development of frozen food products with improved properties. (C) 2004 Elsevier Ltd. All rights reserved.