Controlling lipid digestion by encapsulation of protein-stabilized lipid droplets within alginate–chitosan complex coacervates

The control of lipid digestibility within the human gastrointestinal tract is important for the development of many functional food and pharmaceutical products. This article describes the preparation, characterization, and in vitro digestibility of lipid droplets encapsulated within hydrogel beads. Protein-stabilized lipid droplets were first coated with an alginate layer, and then they were trapped within chitosan/calcium alginate coacervates. The filled hydrogel beads were formed using two methods: “direct method” – add a suspension of alginate-coated lipid droplets to a calcium/chitosan solution; “indirect method” – add chitosan solution to a suspension of alginate-coated lipid droplets and calcium. The in vitro digestibility of the encapsulated lipid droplets was then monitored using a pH-stat method to simulate the small intestine. For both methods, the filled hydrogel beads were relatively stable to aggregation/dissociation from pH 1 to 6, but underwent extensive aggregation and sedimentation at higher pH values. Relatively small hydrogel beads (d < 50 μm) caused a moderate delay in the rate of lipid digestion, while large hydrogel beads (d > 100 μm) could delay the digestion rate appreciably. This study has important implications for designing delivery systems that control lipid digestion by encapsulating lipid droplets within hydrogel beads.