Benzenedialdehyde-crosslinked gelatin nanoparticles for Pickering emulsion stabilization

In this work, three types of benzenedialdehydes (1,2-, 1,3-, and 1,4-BDAs) were used to prepare BDA-crosslinked gelatin nanoparticles and the 1,2-BDA-crosslinked gelatin nanoparticle was explored to stabilize fish oil-loaded Pickering emulsions. The nanoparticle preparation was dependent on both pH and crosslinker types. 1,2-BDA and preparation pH of 12.0 induced the most nanoparticle amounts among the three BDAs and a pH range of 3.0-12.0. The crosslinked gelatin nanoparticles (10-nm scale) could aggregate to form larger nanoparticles (hundred-nanometer scale) in the water. The BDA crosslinking induced lower emulsifying properties (EAI: 10.2 ± 0.3 m²/g; ESI: 69.7 ± 3.6 min) for gelatin nanoparticles than gelatin (EAI: 30.9 ± 0.6 m²/g; ESI: 267.8 ± 2.0 min). With the increase of the gelatin nanoparticle concentrations (5-40 g/L), the emulsion viscosity increased (163 ± 9-422 ± 3 mPa s at the rotary speed of 60 rpm), the interfacial tension decreased (10.3 ± 0.2-7.2 ± 0.2 mN/m), and the creaming indexes decreased (42.1% ± 0.7%-13.3% ± 0.8% at day 21). The higher sodium chloride concentration (0.0-0.8 mol/L) induced the lower emulsion stability, even obvious phase separation (0.8 mol/L of NaCl). Therefore, the sodium chloride addition should be carefully considered for the development of emulsion-based foods. This work provided useful information for the development and application of protein nanoparticles.