Creaming and oxidative stability of fish oil-in-water emulsions stabilized by whey protein-xanthan-locust bean complexes: Impact of pH.

The impact of pH on the physicochemical properties of 10% menhaden oil-in-water (O/W) emulsions containing 2% whey protein isolate (WPI) and 0.1% xanthan (XG)-locust bean gum (LBG) mixtures was investigated. The O/W emulsions containing 0.1% XG-LBG mixtures were compared to emulsions with 0.1% XG and 0.1% LBG. The results indicated that stability is dependent on pH and biopolymer type. At both pH 3 and 5, emulsions containing either XG or XG-LBG mixtures had large particle sizes, viscosity, droplet aggregation, and creaming index, resulting in poor physical stability which can be related to the adsorbed protein-polysaccharide interactions. At pH7, the XG-LBG emulsions showed the greatest resistance to phase separation and resulted in stable emulsions. Lipid oxidation measurements also indicated that XG-LBG mixtures can be used to form stable emulsions at pH 3 and pH 7. These results have significant implications for the development of novel structures containing lipid phases susceptible to lipid oxidation.