Review on the Stability Mechanism and Application of Water-in-Oil Emulsions Encapsulating Various Additives

Water-in-oil (W/O) emulsions can be used to encapsulate and control the release of bioactive compounds for nutrition fortification in fat-based food products. However, long-term stabilization of W/O emulsions remains a challenging task in food science and thereby limits their potential application in the food industry. To develop high-quality emulsion-based food products, it is essential to better understand the factors that affect the emulsions' stability. In real food system, the stability situation of W/O emulsions is more complicated by the fact that various additives are contained in the products, such as NaCl, sugar, and Other large molecular additives. The potential stability issues of W/O emulsions caused by these encapsulated additives are a current concern, and special attention should be given to the relevant theoretical knowledge. This article presents several commonly used methods for the preparation of W/O emulsions, and the roles of different additives (water- and oil-soluble types) in stabilizing W/O emulsions are mainly discussed and illustrated to gain new insights into the stability mechanism of emulsion systems. In addition, the review provides a comprehensive and state-of-art overview of the potential applications of W/O emulsions in food systems, for example, as fat replacers, controlled-release platforms of nutrients, and delivery carrier systems of water-soluble bioactive compounds. The information may be useful for optimizing the formulation of W/O emulsions for utilization in commercial functional food products.