Enhancing encapsulation of curcumin by pH-driven and sodium alginate blending with ovalbumin as a carrier

Curcumin is a hydrophobic polyphenol with various health benefits, but its poor water solubility and stability limit its application in the food and pharmaceutical industries. In this study, a pH-driven method was developed to prepare ovalbumin (OVA)-curcumin nanocomplexes without organic solvents, reducing the environmental impact. The results showed that curcumin was encapsulated in OVA with a high efficiency of over 95% and remained in an amorphous state within the protein molecules. Molecular docking and spectroscopic analyses revealed that curcumin was mainly bound and stabilized by hydrogen bonds and hydrophobic interactions in the hydrophobic core of OVA. The binding strength of the intermediate stage of the pH-driven method was stronger than that of the final stage, due to the exposure of OVA molecular binding sites and the involvement of electrostatic attraction. Furthermore, the potential of polysaccharide blending to enhance the stability of the nanocomplexes was investigated. The results showed that sodium alginate effectively enhanced the photostability and thermal stability of the OVA-curcumin nanocomplexes by co-solubilization and electrostatic complex formation. In addition, simulated in vitro digestion also demonstrated that the pH-driven method combined with polysaccharide blending increased the bioaccessibility of curcumin in nanocomplexes from 17.79% to 52.54%. Therefore, the pH-driven method coupled with polysaccharide blending ensures the encapsulation and stabilization of hydrophobic bioactive substances for use in their delivery systems to improve bioaccessibility.