Interaction of curcumin with four types of gelatins in nanoparticles: Mechanism and application for emulsion stabilization

The research of the interaction between proteins and functional active substances in the protein nanoparticles is a research hotspot in the field of food science. Gelatin type had a significant effect on the structural and functional properties of gelatins. Herein, the interaction mechanism of curcumin with four types of gelatins (bovine bone gelatin, BBG; cold water fish skin gelatin, CFG; fish gelatin, FG; and porcine skin gelatin, PSG) and the structural and functional properties of gelatin/curcumin nanoparticles were explored. All four types of gelatins could be applied to prepare gelatin/curcumin nanoparticles with an amorphous state of curcumin. The nanoparticle sizes were not dependent on the molecular weight of gelatins. The stability of gelatin/curcumin nanoparticle solutions was dependent not on the nanoparticle size but on the gelatin type. The binding affinity between gelatins and curcumin was dependent on gelatin type and the number of binding sites was nearly 1. The main binding forces to form gelatin-curcumin nanoparticles were hydrogen bonds, Pi-alkyl interaction, and Pi-anion interaction. The nanoparticulation increased the surface hydrophobicity of BBG, FG, and PSG, whereas it decreased the surface hydrophobicity of CFG. The nanoparticulation increased the surface tension of gelatins and decreased the dynamic interfacial tension of gelatins. The functional properties were dependent on both gelatin type and nanoparticulation. CFG/Cur nanoparticulation could not change the creaming stability, whereas other gelatins/curcumin nanoparticulation significantly increased creaming stability than the corresponding gelatins. This work provided the basic knowledge to illustrate the interaction and application of protein nanoparticles for Pickering emulsion stabilization.