Recent Advances in Protein-Based Multilayer Emulsions: Fabrication, Characterization, and Applications: A Review

Many bioactive substances have excellent functional properties, including anti-oxidation, anti-inflammatory, and anti-tumor; however, they are often susceptible to degradation by external factors such as light, heat, pH, and ionic strength. To improve stability and bioavailability, various methods have been developed to encapsulate bioactive substances. Emulsion approaches have shown excellent performance for the encapsulation, controlled release, and targeted delivery of bioactive substances. However, a single emulsification material is not sufficient to keep complex foods stable over a wide range of conditions of pH, storage time, and temperature. Improved food emulsions can be designed by combining emulsifiers with distinct properties to meet the range of necessary requirements. For example, the formation of multilayer interfaces around oil droplets, using layer-by-layer self-assembly in oil-in-water emulsions, can improve the quality and stability of many foods. This technology allows the gradual adsorption of various components, including polyelectrolytes, nanoparticles, proteins, and enzymes, and allows for the formation of a multilayer shell with nanometer thickness and high stability. This paper reviews latest developments in the preparation, characterization, and application of multilayer emulsion delivery systems for bioactive substances. Furthermore, we discuss next steps in the development of multilayer emulsions to achieve effective encapsulation and delivery of bioactive substances.