Internal and external factors affecting the stability of glycerol monostearate structured emulsions
Monoglyceride (MG) structured emulsions have been developed for use in diverse food and cosmetic applications. However, these MG-structured emulsions undergo a polymorphic transformation from the α-gel phase to the coagel phase, resulting in emulsion destabilization and water syneresis. In this study, the stability of emulsions containing 60–70% (w/w) water structured with 5% (w/w) of a blend of the emulsifier glycerol monostearate (GMS) and co-emulsifier sodium stearoyl lactylate (SSL), was assessed. The internal factors examined were concentrations of co-emulsifier and the addition of the polysaccharide xanthan gum. External factors examined included cooling rate and applied shear. The methods used to study the polymorphic transition were differential scanning calorimetry, X-ray diffraction, and pulsed proton nuclear magnetic resonance. In this work, the sub-α Coagel Index was successfully used to characterize the degree of coagel formation in MG-structured emulsions. Results showed that the stability of the α-gel phase was improved by using 1 : 9 w/w SSL : GMS ratios and by adding 0.1% xanthan gum. Slow cooling rates without shear could also increase the stability of the α-gel phase in the structured emulsion system.