Preparation and characterization of porous starch/β-cyclodextrin microsphere for loading curcumin: Equilibrium, kinetics and mechanism of adsorption

In this study, porous starch/β-cyclodextrin microsphere (PCS-CD) was fabricated for the first time through the crosslink reaction between corn starch (CS) and β-cyclodextrin (β-CD) combined with enzymatic hydrolysis . The structure, morphology, particle size, thermal property and pasting property were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), laser light scattering particle size analyzer and differential scanning calorimetry (DSC), respectively. The results showed that the combination significantly increased the adsorption capacity of hydrophobic substance, which was evaluated by oil adsorption (316 g/g), and achieved an improvement of thermal stability (for an increased pasting temp at 86.5 °C) and shearing resistance (for a decreased breakdown viscosity at 148 cP). The water solubility index (WSI), swelling power index (SPI) and paste clarity were decreased after being crosslinked, but increased slightly after enzymatic hydrolysis. Furthermore, the adsorption kinetics and mechanism of curcumin on the PCS-CD were also evaluated. The results of adsorption kinetics showed that the adsorption process could be described by Pseudo-first-order model and was controlled by two or more diffusion mechanism. The free energy calculated by adsorption isotherm model was 0.1017 kJ/mol, which revealed that a physical-controlled adsorption was occurred between the PCS-CD and curcumin.