Encapsulation of curcumin in ZEIN-HTCC complexes: Physicochemical characterization, in vitro sustained release behavior and encapsulation mechanism

In order to improve the water solubility and stability of curcumin (CUR) and achieve its sustained release, the ZEIN–N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (HTCC) complexes were designed to encapsulate CUR using an antisolvent precipitation (ASP) method. The encapsulation efficiency (EE) and loading capacity (LC) of curcumin in ZEIN-HTCC complexes were 92.2% and 0.6%, respectively. After encapsulation, the resistance of curcumin to thermal, natural light and UV irradiation, as well as the antioxidative activity were improved significantly (P < 0.05). ZEIN-HTCC-CUR complexes exhibited good redispersibility and enhanced the water solubility of curcumin. In vitro simulated digestion experiments clarified that the ZEIN-HTCC complexes can control the sustained release behavior of curcumin, and the release kinetics can be fitted by the Higuchi model. Results taken from fluorescence spectra and Fourier transform infrared spectroscopy (FTIR) indicated that hydrophobic interaction, hydrogen bonding and electrostatic interactions were the main driving forces to form the ZEIN-HTCC-CUR complexes. The X-ray diffraction (XRD) results revealed that the encapsulated curcumin was in an amorphous state. The information provided by this study should be of interest to food industry to fabricate robust nanoscale delivery systems with ZEIN-HTCC complexes for CUR and other hydrophobic bioactive compounds.