Delivery of Curcumin Using Colloidal Complexes Formed from Ammonium Chitosan and Acid Treated Soybean Protein

Curcumin (CUR) is found to exhibit a broad spectrum of potentially beneficial biological activities, which make it suitable as a nutraceutical ingredient in functional foods and supplements. But its application for this purpose is often limited by its low water-solubility, chemical stability, and bioavailability. In this study, acid-treated soybean protein isolate (SPI) and chitosan quaternary ammonium salt (CQAS) were used to assemble colloidal carriers for CUR to form soybean protein isolate-curcumin-chitosan quaternary ammonium salt nanoparticles (SPI-CUR-CQAS NPs). The nanoparticles formed were relatively small (< 400 nm), approximately spherical, and strongly positively charged (> 45 mV). Fluorescence spectroscopy demonstrated that the dominant interaction between CUR and SPI was hydrophobic attraction, while the dominant interaction between CQAS and SPI was electrostatic attraction. The encapsulation efficiency (95.4