pH-driven preparation of caseinate-chitosan complex coacervation for co-encapsulation of hydrophobic curcumin and hydrophilic l-ascorbate: Stability and in vitro release properties

Co-encapsulation of bioactive compounds with different functionality in a carrier has received considerable attention, while co-encapsulation of bioactives with different solubility remains a challenge. In this study, the co-encapsulation of hydrophilic l -ascorbate and hydrophobic curcumin was achieved using an organic-free method. The aim of this work was to evaluate the efficacy of chitosan coating loaded with l -ascorbate on the complexation of curcumin with caseinate by investigating their interaction, storage stability and release behavior during simulated digestion. The size and ζ-potential of the optimized chitosan-caseinate binary particles at pH 5.0 were 582 nm and 28 mV, respectively. l -ascorbate electrostatically interacted with chitosan and then coated on the caseinate particles where hydrophobic curcumin was encapsulated. The encapsulation efficiency of curcumin and l -ascorbate was 96.2% and 47.6%, respectively. l -ascorbate-loaded chitosan coating significantly improved the storage and irradiation stability of curcumin and inhibited the structural changes of caseinate induced by the loaded curcumin after storage. The antioxidant activity of the co-delivered system was significantly improved compared with either individual system and basically unchanged during irradiation. These results may serve as a helpful guide for future study on the optimization of core-shell particles for the co-delivery of multiple bioactive compounds.