Modulating lipid droplet intestinal lipolysis by electrostatic complexation with anionic polysaccharides: Influence of cosurfactants

The food, supplement, and pharmaceutical industries are interested in developing delivery systems that can control the biological fate of ingested lipids within the gastrointestinal tract. In this study, a simulated intestinal lipolysis model was used to elucidate the impact of cosurfactants and anionic polysaccharides on the digestion of emulsified fats. Lipid droplets were prepared by membrane homogenization using a globular protein (β-lactoglobulin) as the primary surfactant, and a non-ionic surfactant (Tween 20) as the cosurfactant. Electrostatic complexes were formed by mixing the resulting cationic lipid droplets with anionic alginate molecules. In the absence of cosurfactant, multilayer emulsions were formed consisting of lipid droplets coated by a layer of alginate. In the presence of cosurfactant, microclusters were formed that contained aggregates of alginate-coated lipid droplets linked together. The electrical charge on the complexes remained negative from pH 2 to 7.5, with the complexes formed in the presence of cosurfactant having a lower charge magnitude. The rate and extent of lipid digestion under simulated intestinal lipolysis conditions depended on cosurfactant, alginate, and digestion conditions (fasted versus fed). Under high calcium fed conditions (20 mM Ca2+), lipid digestion was highly suppressed in delivery systems containing alginate but no cosurfactant, which was attributed to the formation of a calcium alginate gel that restricted access of lipase to the lipid droplets. This reduction in lipid digestion could be largely overcome by including cosurfactant in the delivery systems. The information obtained in this study may prove useful for designing oral delivery systems that control the digestion and release of lipids in the gastrointestinal tract.