Oleogelating properties of ethylcellulose in oil-in-water emulsions: The impact of emulsification methods studied by 13C MAS NMR, surface tension and micropipette manipulation studies

Abstract

This study addressed the oleogelating properties of EC when EC-oleogel microdroplets are dispersed in an aqueous medium. By measuring the interfacial tension between oil-water, EC was found to be interfacial active. Oleogel-in-water emulsions were prepared by two different emulsification methods termed hot and cold. The first included high pressure homogenization of EC-oil and water at a temperature above the gelling point of EC, whereas the latter implied dispersion of set EC-oleogels in water by high speed mixing at a temperature below the melting point of EC-oleogels. The oleogelling functionality was lost when hot emulsification was applied. Instead EC migrated to the interface of oil and water and formed a shell around oil droplets which was assessed by micropipette manipulation techniques. On the other hand, the oleogel remained stable when EC-oleogel was dispersed in water using the cold emulsification method. For this system a fraction of the triglycerides in oil was immobilized in a similar manner as oil in bulk oleogels and the mechanical properties of dispersed droplets were no longer reflecting the flow behavior of low viscous oil, which indicates oil gelation by EC.