Enhanced bioaccessibility and stability of iron through W/O/W double emulsion-based solid lipid nanoparticles and coating with water-soluble chitosan

W/O/W double emulsion-based iron-solid lipid nanoparticles (Fe-SLNs) and water-soluble chitosan-coated Fe-SLNs (WSC-Fe-SLNs) were developed to increase the bioaccessibility and stability of iron. Fe-SLNs exhibited a small diameter (158.17 ± 0.72 nm) and adequate zeta potential (-34.31 ± 0.41 mV) to maintain stable dispersion. The coating with WSC resulted in an increase in particle diameter (up to 226.13 ± 1.97 nm) and change of zeta potential to positive value (+47.83 ± 1.24 mV) because of the amine groups of chitosan. The lipid peroxidation of the Fe-SLNs and WSC-Fe-SLNs was substantially lower than that of pure iron. Both Fe-SLNs and WSC-Fe-SLNs were also able to protect the encapsulated iron in simulated gastric fluid, while effectively releasing almost 80% of the iron in simulated intestinal fluid. The Fe-SLNs and WSC-Fe-SLNs showed a great potential as functional materials to apply to various food industries through enhancement of physical stability and bioaccessibility of the encapsulated iron.