Interactions of milk protein-stabilized oil-in-water emulsions with bile salts in a simulated upper intestinal model

For β-lg-stabilized droplets, ζ-potential significantly changed from −63.1 ± 0.5 mV to −37.2 ± 0.3 mV in presence of bile salts due to competitive interfacial displacement of β-lg by bile salts as characterized by SDS-PAGE analysis of the continuous phase. On the other hand, lactoferrin-stabilized emulsion droplets showed considerable aggregation in presence of intestinal electrolytes alone at pH 7.5. The ζ-potential values of lactoferrin emulsion decreased gradually from +53.5 ± 0.6 mV to −12.2 ± 0.2 mV in presence of bile salts due to certain electrostatic effects (e.g. pH shift towards the isoelectric point, binding of anionic bile salts to cationic interfacial lactoferrin layer) in comparison to the behaviour of β-lg-stabilized droplets.