Nanoemulsions: Using emulsifiers from natural sources replacing synthetic ones—A review

In recent years, substantial consideration within the food industry has been aimed at the development of food-grade nanoemulsions (NE) as promising systems for encapsulating, stabilizing, and delivering bioactive compounds. Although numerous studies have revealed the critical potential of NE, there are still several challenges to overcome them. These include the extensive amounts of synthetic emulsifiers needed for NE formulation, which can potentially be toxic for human health. The interest in safety, and natural emulsifiers have stimulated food manufacturers to develop "label-friendly" formulations by replacing synthetic emulsifiers with natural alternatives. This review represents a critical and comprehensive summary of the application of natural emulsifiers as potential substitutes for synthetic emulsifiers in NE production, with particular emphasis on the newly identified natural emulsifiers. Some recent reports showed the excellent emulsifying properties of various natural emulsifier extracted from natural resources, to produce NE, and therefore, might be generalized for further industrial applications. Future trends are encouraged to identify novel natural emulsifiers from industrial food by-products that may demonstrate highly effective emulsifiers.