Preparation, structure-property relationships and applications of different emulsion gels: Bulk emulsion gels, emulsion gel particles, and fluid emulsion gels

In recent years, there has been increasing interest in emulsion gels, due to their better stability during storage and potential for prolonged intestinal drug release compared to emulsions. There are three kinds of emulsion gels, classified according to their morphological properties: bulk emulsion gels, emulsion gel particles and liquid emulsion gels. This paper provides a comprehensive review of the mechanisms and procedures of different methods for preparing different emulsion gels and relationships between structures and properties of emulsion gels. The applications of emulsion gels in the food industry are finally discussed. Different emulsion gels result from different preparation methods, and have various structure-property relationships and applications. Many methods can be used to prepare bulk emulsion gels, involving different matrix materials, processing techniques, and purposes. This can result in different structures of gel matrices and emulsion droplets, and interactions between them, which can influence the structures of bulk emulsion gels and then their mechanical and release properties. On the other hand, extrusion and impinging aerosol methods are two methods for preparing emulsion gel particles, while liquid emulsion gels can be prepared by Pickering emulsions and disrupted gel systems. Rheological, syneresis and swelling properties are critical for gel particle suspensions, while flow behavior and release properties are important to liquid emulsion gels. In addition, fat replacements and delivery systems are main applications of emulsion gels in the food industry. However, current research has mainly focused on bulk emulsion gels, so further studies on emulsion gel particles and liquid emulsion gels are required.