Ultrasonic cavitation assisted synthesis of multilayer emulsions as encapsulating and delivery systems for bioactive compounds

This chapter discusses the basic aspects of the oil-in-water emulsion and their application for the encapsulation of bioactive compounds. The role of emulsifiers and need of homogenization in their formation and stabilization has been explained. The fundamentals of ultrasonic homogenization and its comparison with other high energy methods such as high-pressure homogenization and microfluidization are also discussed. The main emphasis in this chapter is on the formation of multilayer emulsions prepared in a layer-by-layer approach and their potential applications for the encapsulation and delivery of bioactive lipophilic compounds. For the successful encapsulation and delivery, it is necessary to identify the kinetic stability of the delivery system, and it has been found that the multilayer emulsion is the most stable system against variations in the physicochemical conditions such as pH, temperature, and lipid autooxidation. In addition, case studies related to the preparation of multilayer emulsions using ultrasonication have been discussed, which includes the detailed process optimization and performance evaluations for the encapsulation and controlled release of curcumin under the simulated intestinal conditions.