New insights into water-in-oil-in-water (W/O/W) double emulsions: Properties, fabrication, instability mechanism, and food applications

Nowadays people demand for healthy, convenient, and wholesome foods. Double emulsions have attracted widespread attention in the food industry owing to their capability of encapsulating the compounds, fabricating polymersomes, and acting as fat replacers or sweetness enhancers in different foods. In this review, properties and their importance in the fabrication of double emulsions along with their advantages and disadvantages are discussed. In the lateral part of the manuscript, the instability mechanism and the effect of different variables on the stability of the double emulsions are reviewed. Finally, this review provides a glimpse of the recent food application of W/O/W double emulsions. Double emulsions have a better profile on the encapsulation of nutrients along with maintenance of the organoleptic quality of the food. The conventional emulsification techniques result in low encapsulation efficiency and poor monodispersity. With recent developments, different novel methods for the fabrication of double-emulsions have been developed such as glass capillary microfluidic devices, membrane emulsification, phase inversion techniques, etc. However, findings thus far indicate that the long-term stability of double emulsions remains a crucial issue that limits their wide application in food formulations. Therefore, further research should focus on finding innovative approaches to improve the stability of double emulsions.