Abstract: In order to improve the apparent solubility of curcumin (CCM), phytoglycogen (PG) was used as the carrier to load CCM, yielding phytoglycogen-curcumin complex (PG-CCM). The effects of PG concentration, CCM concentration, pH, and ion concentration on the apparent solubility of CCM were examined. Dynamic laser light scattering was used to study the particle size distribution of the composite, and the morphology was observed by transmission electron microscopy. The interaction between PG and CCM as well as changes in the state of CCM and the microenvironment surrounding CCM before and after loading onto PG was investigated by infrared spectroscopy, differential scanning calorimetry (DSC) and fluorescence spectroscopy. The results indicated that PG was an efficient carrier for CCM and PG-CCM significantly increased the apparent solubility of CCM. The loading efficiency was found to be related to the concentrations of PG and CCM. The loading system was sensitive to pH, but immune to low concentration ions. The apparent solubility of 4 mg/mL CCM loaded on 10 mg/mL PG at pH 7 was 18.68 μg/mL. The average particle size of the composite nanoparticles, electrically neutral, was 70–75 nm, and the particle size distribution was uniform; the carrier PG presented a smooth spherical structure, while the PG-CCM complex presented a large, irregular planar sheet. CCM in the complex existed in an amorphous structure. Hydrogen bonding was the main interaction between CCM and PG. CCM shifted from a more polar microenvironment to a less polar region under the action of PG. This study concludes that PG is an efficient carrier and the preparation of PG-CCM is simple and can significantly improve the apparent solubility of CCM. It is expected to broaden the application of CCM in the food industry.

Key words: phytoglycogen (PG), curcumin (CCM), solubility, structure characterization