Improved antioxidant activity and physicochemical properties of curcumin by adding ovalbumin and its structural characterization

Protein as a carrier to improve the solubility and bioavailability of curcumin has been studied widely. However, to date the researches were mainly focused on its binding mechanism and the applications in aqueous solution. Systematic study on the characteristics and properties of the complex in solid phase after the binding of curcumin with protein is scarce. In this work, a powder composite of curcumin bound to ovalbumin was prepared by freeze-drying. The FTIR and X-ray diffraction results indicated that the crystal structure of curcumin and secondary structure of ovalbumin were changed because of the binding of curcumin to ovalbumin, leading to the formation of an amorphous complex with the sizes in the range of 924.20 ± 72.34 nm. Thermogravimetric analysis showed that the maximum weight loss point of ovalbumin/curcumin complex was at 289 °C, which was lower than that of pure ovalbumin and curcumin, implying that the complex was more prone to pyrolyze. Furthermore, the improved antioxidant activity was evaluated by DPPH radical scavenging activity and reducing power assay compared with pure ovalbumin and curcumin. This work could help to understand the characteristics of the curcumin-protein complex which has the potential to be applied in functional foods.