Impact of chelators on the oxidative stability of whey protein isolate-stabilized oil-in-water emulsions containing ω-3 fatty acids

The oxidative stability of oil-in-water emulsions can be improved by engineering the surface of the emulsion droplets to decrease transition metal–lipid interactions. This can be accomplished in protein-stabilized emulsions where the pH is less than the pI of the protein and the emulsion droplets are cationic. While these emulsions have high oxidative stability, little is known about whether metal chelators can be used to further decrease lipid oxidation. Therefore the purpose of this research was to investigate the impact of ethylenediamine tetraacetic acid (EDTA), citrate and polyphosphates on the physical and oxidative stability of algae oil-in-water emulsions, stabilized by whey protein isolate. Chelators were added to emulsions at concentrations ranging from 1 to 100 μM and lipid oxidation was monitored with lipid hydroperoxides and headspace propanal. The oxidative stability of whey protein isolate-stabilized emulsions, at both pH 3.0 and 7.0, was improved by EDTA at concentrations ⩾1 μM. Neither citrate nor polyphosphates were effective at inhibiting lipid oxidation at the concentrations tested. None of the chelators tested had any impact on the physical stability of the emulsions. These results indicate that the oxidative stability of whey-protein isolate-stabilized oil-in-water emulsion can be increased by EDTA without having any impact on physical stability.