Destabilization of protein-based emulsions by diglycerol esters of fatty acids – The importance of chain length similarity between dispersed oil molecules and fatty acid residues of the emulsifier

Destabilizing effects of diglycerol mono-esters of different saturated or one mono-unsaturated fatty acids (DF) on protein-based emulsions prepared with various types of oil were examined by visual observations and particle size analyses. By diglycerol esters of oleic acid (DO), a hexadecane-in-water emulsion was more obviously destabilized than an octadecane-in-water emulsion or food oil-in-water emulsions. Interfacial tension measurements indicated that the adsorbed protein on oil droplet surfaces of hydrocarbon emulsions can be more easily displaced by DO compared to the case of food oil emulsions. The degree of hydrocarbon emulsion destabilization by DO varied with the chain length of hydrocarbon molecules. From the results of combination tests of five hydrocarbons varying in chain length in oil phase and five DF having different mono-fatty acid residue, we described a possibility that DF could effectively destabilize the hydrocarbon emulsion when the chain length of fatty acid residue of DF was similar to that of hydrocarbon molecules.