Food-grade nanoemulsions and their fabrication methods to increase shelf life

In recent years, there has been an increasing interest in the utilization of emulsion and food-grade nanoemulsions and their fabrication methods, and methods have evolved in the food industry and other fields. Emulsions, according to droplet diameter and stability, are divided into three important groups of conventional emulsions, nanoemulsions, and microemulsions; therefore, nanoemulsions are a class of emulsions. The small and fine size of the droplet in nanoemulsions (i.e. droplet diameter <100nm) make them applicable in some fields, due to their enhanced bioavailability, solubility, better stability against gravitational separation, appropriateness for delivery of lipophilic active agent’s components, high surface area per unit volume and antimicrobial property. Also, they need less surfactant in comparison with other constructions. There are many kinds of preparation methods that can be classified into low-intensity and high-intensity approaches. The basis of the high-intensity procedure is mechanical energy that comes from flows like cavitation, but the low-intensity procedure is based on physicochemical processes. The most notable ways in high-energy emulsification are high-pressure valve homogenization, microfluidization, ultrasonication, rotor-stator emulsification, and membrane emulsification. Low-energy emulsification is divided into thermal and isothermal methods for nanoemulsions fabrication. Thermal methods consist of phase inversion temperature (PIT) and isothermal methods consist of spontaneous emulsification (SE) and emulsion phase inversion (EPI). Also, today, there is a lot of evidence to compare the low-intensity approach with high-intensity one and some of them express that in the low-energy method, equipment is not expensive and special and this is a very important advantage in saving energy. Also, some researchers express that in the high-energy method, we need much less concentration of surfactant for the formation of small size droplet.