Evaluating the curcumin-loading ability of a complex of zein and nuclei formed from fibrillar whey protein isolate

Nuclei refers to the intermediate product formed at the initial stage of protein fibril aggregation, which has a high activation energy, stable structure, and is resistant to hydrolysis. Nuclei was obtained from fibrillar whey protein isolate. Zein-nuclei core-shell nanoparticles were utilized to encapsulate curcumin. As the ratio of zein to curcumin decreased from 40:1 to 4:1, the particle size increased from 144.77 to 157.00 nm, accompanied by morphological transition from stranded to spherical structure. The optimal zein-to-curcumin ratio was 10:1, at which the complex exhibited the highest encapsulation efficiency (92.65%) and loading capacity (8.35%). Complex formation was driven by hydrogen bonding, electrostatic interactions, and hydrophobic effects. Moreover, the addition of curcumin induced structural modifications in the zein-nuclei binary complexes, which in turn influenced their thermal stability. The thermal stability of curcumin were significantly enhanced upon encapsulation within the zein-nuclei core-shell nanoparticles. Moreover, the release of curcumin was markedly delayed in simulated gastrointestinal fluids when encapsulated in these complexes. These findings demonstrate that zein-nuclei core-shell nanoparticles represent a promising encapsulation system for curcumin in the food industry.