Preparation of whey protein isolate-iron-curcumin ternary composite nanoparticles and investigation of formation mechanism

Whey protein isolate (WPI) exhibits mineral binding and acts as a potentially versatile carrier of the nutritional properties of curcumin. This study aimed to investigate the synthesis of WPI-Fe-Curcumin by combining iron and curcumin with WPI, to determine whether the antioxidant capacity of curcumin can protect the high-quality iron source Fe²⁺ when it binds to divalent iron ions, to describe the mechanism of WPI-Fe-Curcumin complex formation and to investigate the solubility stability of the complex. The results showed that (i) The iron content was 3.561 mg/g protein, and the encapsulation efficiency for curcumin was 99.98% efficiency. (ii) After dehydration, the high solubility of the WPI-Fe-Curcumin dry powder was 85.41% at 0 day and 82.84% at day 30. (iii) The addition of curcumin resulted in a 6.04% increase in Fe²⁺ content, indicating that curcumin provided an antioxidant reducing environment for the iron ions. (iv) The introduction of iron reduced the particle size and promoted the formation of β-sheet structures of whey protein. These results suggest that WPI-Fe-Curcumin can facilitate the development of effective nutrient delivery systems for applications in food, iron supplement, and pharmaceutical industries.