Fabrication and Characteristic of Rhamnolipid-chitosan Coated Emulsions for Loading Ergocalciferol

To overcome the intrinsic limitations of ergocalciferol, layer-by-layer oil-in-water emulsions were formulated and applied in the microencapsulation of ergocalciferol. The primary emulsions were prepared using rhamnolipids to stabilize oil droplets, and then the secondary emulsions were formed by electrostatic deposition of cationic chitosan onto anionic rhamnolipids-coated droplets. The effects of pH, ionic strength, and thermal treatment on the stability of emulsions were investigated. Secondary emulsions were more stable than primary emulsions at low pH and high NaCl concentrations. Both emulsions showed excellent physicochemical stability during long-term storage. The droplet size of ​emulsions remained stable, and the ergocalciferol retention in emulsions was still maintained at over 95% after 30 days of storage. These results indicate that the resistance of prepared emulsions to different environmental stresses is enhanced. Moreover, this study gives important information for extending the utilization of rhamnolipids and chitosan in the delivery system for functional ingredients.