Modulation of physicochemical properties of lipid droplets using β-lactoglobulin and/or lactoferrin interfacial coatings

There is considerable interest in the development of food-grade delivery systems to encapsulate, protect and release bioactive lipids. In this study, emulsion-based delivery systems were prepared consisting of lipid droplets covered by β-lactoglobulin (BLG) and/or lactoferrin (LF) coatings. BLG and LF are globular proteins with relatively low (pI∼5) and high (pI∼8) isoelectric points, respectively. Mixed systems were prepared by adding LF to BLG-stabilized corn oil-in-water emulsions (BLG/LF-coated droplets) or by adding BLG to LF-stabilized corn oil-in-water emulsions (LF/BLG-coated droplets) at pH 7, where there is an electrostatic attraction between the proteins. The influence of pH (3-7), ionic strength (0-60mM CaCl₂ or 0-200mM NaCl, pH 7), and thermal treatment (21-90°C, pH 7, 20min) on the physical stability of the resulting emulsions was examined. Emulsions with good stability to pH, salt, and thermal processing could be created using mixed interfacial coatings. In addition, we found that the lipids in these emulsions could still be digested using an in vitro digestion model to simulate small intestine conditions. This work may lead to the formation of emulsion-based delivery systems with improved physicochemical and functional performance.