Protein-based emulsion gels as materials for delivery of bioactive substances: Formation, structures, applications and challenges

Protein-based emulsion gels (PEGs) can provide a stable network structure and improve the physical and chemical stability and texture of substances. PEGs have adjustable viscoelasticity and can be used for stable loading and controlled release of functional substances. Current research has focused on the construction of PEGs and the encapsulation of functional ingredients to obtain functional foods with desirable textures. The development of multiple types of PEGs has provided a wider choice of raw material combinations and textures for PEGs as materials for delivering functional factors, and the delivery of bioactive substances has become more feasible. To further understand the application of PEGs as biomaterials in delivering bioactive substances, we reviewed the preparation methods, formation mechanisms, and structural design principles of PEGs, emphasizing the relationship between emulsion gel structure and functional properties. Then, recent advances in the loading of bioactive substances (targeted delivery, protection of bioactive substances, and improvement of drug utilization) of PEGs were summarized. Finally, the opportunities and challenges for the future development of PEGs as a material for loading bioactive substances were presented. The structural design principles of PEGs-interfacial structure design, cross-linked structure design, and adjustable viscoelastic structure design make PEGs designable and reproducible as a biomaterial. In addition, PEGs have unique physicochemical properties and functional properties, having the feasibility to be developed as delivery materials in multiple industries. This review emphasizes the importance of recognizing the material properties of PEGs and aims to provide potential new uses for PEGs as biomaterials.