Assembly mechanism and interfacial behavior of potato protein-zein nanoparticles

The low solubility of potato protein isolate (PPI) limits its application in the food industry. In this study, we prepared PPI-zein nanoparticles with PPI as a shell and zein as a core in a "core-shell" structure by pH-cycle method. Compared with PPI, the soluble protein content increased from 73.39 % to 85.93 % after zein was added. After the formation of PPI-zein nanoparticles, the content of α-helix decreased by 4.0 %, and the structure became looser. Molecular dynamics simulation showed that the conformation and flexibility of peptide 246-267 in patatin changed significantly, which may be the sites of its interaction with zein. The binding free energy and residue energy decomposition analysis showed that hydrophobic interaction was the main force to stabilize the complex, and the bond length formed by Leu-320 and Leu-6 was the shortest (0.32 nm), and the force was the strongest. Furthermore, when the mass ratio of PPI to zein was 7: 3, the particle size of the nanoparticles reached the minimum (134.03 nm), which was beneficial to its rapid diffusion at the interface ( K diff = 4.451). The expanded elastic modulus ( E d ) was always greater than the expanded viscous modulus ( E v ), forming an elastic interfacial film. The PPI-zein nanoparticles had better storage stability and environmental stability than PPI. This work may provide a scientific basis for the application of hydrophobic plant proteins as soluble nanoparticles in food.