Protein nanoparticles for Pickering emulsions: A comprehensive review on their shapes, preparation methods, and modification methods

Background: Protein nanoparticles are promising candidates for the preparation and stabilization of Pickering emulsions. The research and development of protein nanoparticles with different shapes is one of the hotspots in the field of Pickering emulsions because of their significant advantages such as natural sources, non-toxicity, easy extraction, acceptance in food industry, good surface activity, and good emulsion stabilization abilities. Scope and approach: This paper firstly reviews the shapes of protein nanoparticles for the stabilization of Pickering emulsion. Secondly, the paper summarizes the preparation methods of protein nanoparticles for the stabilization of Pickering emulsions. Thirdly, the paper discusses the modification of protein nanoparticles with other substances at oil/water interface. Finally, this paper provides a brief summary and outlook of research and development of protein nanoparticle for Pickering emulsions. Key findings and conclusions: Until now, the shapes of the applied protein nanoparticles for Pickering emulsions can be classified into six types: undeformable solid spherical nanoparticles, nanofibrils, nanotubes, nanogels, nanocages, and plate-shaped nanoparticles. According the physical and chemical differences of preparation process, the preparation methods of protein nanoparticles for the stabilization of Pickering emulsions can be classified into natural self-assembly, physical, chemical, and enzymatic methods. The modification methods of protein nanoparticles with other substances at oil/water interface can be classified into physical mixing and chemical crosslinking. This work can provide basic information on the properties of protein nanoparticle and Pickering emulsions. It can also guide the research and development of protein nanoparticles for the stabilization of Pickering emulsions.