Zein-based core-shell microcapsules for the potential delivery of algae oil and lipophilic compounds

Due to the benefits involving brain development and cardiovascular health, algae oil which is rich in omega-3 fatty acids has become a popular dietary supplement in recent years. However, the incompatibility with water and poor oxidative stability limits its addition in foods and beverages. In this work, the formation and characterization of zein-based core-shell microcapsules with tunable shell thicknesses for the potential delivery of algae oil were reported. They were prepared based on the in situ precipitation of zein from the continuous phase onto the surface of oil droplets by self-assembly at a refrigerated temperature without any need for surfactants and cross-linkers. The shell thickness could be controlled by the ratio of algae oil to zein (O/Z), which was indicated by their characterization including static light scattering, confocal laser scanning microscopy and scanning electron microscopy. Evidence from the peroxide value and the hexanal level of the emulsions in a thermally accelerated storage test suggested that the oxidation degree of the loading algae oil was negatively correlated with the shell thickness of the capsules. Furthermore, the release profiles of vanillin, which was used as a model volatile lipophilic compound and masking agent for the off-flavor from algae oil, could be tuned by manipulating their shell thickness. This suggested that the all-natural edible core-shell microcapsule might further be used as a model system for the delivery of lipophilic compounds. They may further promote the sustainable use of underutilized water-insoluble proteins as functional biomaterials in functional foods and pharmaceutical applications.