Properties of Pickering emulsion stabilized by food-grade gelatin nanoparticles: influence of the nanoparticles concentration

In this study, the food-grade gelatin nanoparticles (GNPs) prepared by genipin cross-linking were applied to stabilize Pickering emulsion. The properties of Pickering emulsion stabilized by different GNPs concentrations (0.3-2.0 wt%) were investigated systematically, including the optical microscopy, droplet size, flocculation index (FI), rheological behavior, water holding capacity (WHC), protein adsorption rate (AP), interface protein content (Gamma), interfacial pressure (pi) and Confocal Laser Scanning Microscopy (CLSM). The results showed that increasing GNPs concentration could obviously increase the pi value of GNPs, thus enhancing GNPs adsorption (AP and Gamma) at the oil-water interface and the formation of network structure (CLSM), consequently resulting in a smaller droplet size and FI of the Pickering emulsion. Furthermore, the increase of AP resulted in the increase of apparent viscosity and modulus, and the formation of a more compact network structure, thus improving the WHC and stability of the Pickering emulsion. Therefore, the properties of the Pickering emulsion could be adjusted by changing the GNPs concentration. The Pickering emulsion with relatively low viscosity, good mobility and stability could be prepared at 0.5 wt% GNPs concentration, the Pickering emulsion with high viscosity and stability could be prepared at 1.0 wt% GNPs concentration, and the Pickering emulsion with prominent viscoelasticity and stability could be prepared at 1.5-2.0 wt% GNPs concentration. This study could provide important implications for the development of food-grade Pickering emulsion based on gelatin nanoparticles.