Synthesis and release studies of microalgal oil-containing microcapsules prepared by complex coacervation

Microalgal oil was encapsulated in gelatin-gum Arabic complex coacervated matrices using transglutaminase (TG) as cross-linking agent. The effects of various cross-linking parameters including hardening time, temperature, pH and TG concentration on the oil release rate of the complex coacervation microcapsules (CCMs) were investigated, with sodium dodecyl sulfate (SDS) as release medium. The optimum parameters were as follows: hardening for 6h at 15°C and pH 6.0 with TG concentration of 15 U/g gelatin. The microcapsules obtained under optimum conditions had the lowest oil release rate. By analyzing the oil release curves, it was found that the oil release rate did not exactly fit the modified first-order kinetic model but exhibited early time and late time approximations for unsteady state diffusion. A greater initial release of oil was clearly observed whatever cross-linking parameters were, while the release profile became constant indicating some sustained release after the first hour.