Advances of biopolymer-based emulsion gels: Fabrication, design, and application

Background

Biopolymer-based emulsion gels are soft solids that consist of oil droplets embedded with a hydrogel matrix, which may be assembled from proteins and/or polysaccharides. Individual biopolymers may form hydrogels through a variety of mechanisms, which leads to emulsion gels with different physicochemical and functional properties. The hydrophobic domains within the oil droplets embedded in emulsion gels can be used to encapsulate lipophilic bioactive substances, as well as to protect them and control their release.

Scope and approach

This article reviews the design, formation, and application of biopolymer-based emulsion gels. In particular, it describes the different kinds of crosslinking mechanisms that can be used to form hydrogel matrices, as well as their impact on emulsion gel formation, structure, and functionality. The stability, release, and bioavailability of various types of lipophilic bioactive compounds encapsulated within emulsion gels is also reviewed.

Key findings and conclusions

The structure and functionality of biopolymer-based emulsion gels are closely linked, with crosslinking mechanisms determining the network structure and the interactions within the network. Through rational selection of biopolymers and gelation strategies, it is possible to finely regulate texture, encapsulation efficiency, release, and stability. Systems combining proteins and polysaccharides reinforce network stability, while internal and external gelation routes offer improved morphological control and wider applicability. Emulsion gels have been applied as delivery systems for bioactives, as fat replacers, and in 3D printing, with their performance determined by the gelation mechanisms that govern network structure and functional properties.