Controlling the functional performance of emulsion-based delivery systems using multi-component biopolymer coatings

The digestion and release of bioactive lipophilic components encapsulated within emulsion-based delivery systems can be controlled by coating the lipid droplets with biopolymer coatings. In this study, multicomponent biopolymer coatings were formed around lipid droplets using an interfacial electrostatic deposition approach. These coatings consisted of an inner layer of globular protein (B-lactoglobulin), an intermediate layer of cationic polysaccharide (chitosan), and an outer layer of anionic polysaccharide (pectin or alginate). In the absence of the outer anionic polysaccharide layer, the protein chitosan-coated droplets were highly unstable to aggregation at high pH values (pH > 6), due to loss of chitosan charge. In the presence of the outer layer, the droplets had good stability to aggregation from pH 7 to 4, but aggregated at lower pH due to loss of pectin or alginate charge. An in vitro lipid digestion model (pH stat) indicated that polysaccharide coatings reduced the rate of lipid digestibility. These findings have important implications for the design of delivery systems for bioactive lipophilic components in the pharmaceutical, biopharmaceutical, and food industries. (C) 2010 Elsevier B.V. All rights reserved.