Ultrasonic Emulsification:Reduces Droplet Diameter and Enhances Stability

Nanoemulsions are colloidal dispersions of two immiscible liquids (oil and water) with droplet sizes between 20 and 200 nm. The efficient production of nanoemulsions with very low oil droplet sizes facilitates the inclusion of oil soluble bioactive substances into a range of water based foods and also in delivery of lipophilic drugs. Stability of nanoemulsion is one of the major concerns when we consider its applications. With exception to few (as in spontaneous emulsification), energy input is required to formulate nanoemulsion. In this present study, we assessed the effect of ultrasound on stability and droplet size of emulsion. The nanoemulsion formulated by emulsification time of 2 min, 5 min, 10 min and 15 min demonstrated stability for 1 day, 10 days, 30 days and 60 days respectively. Also we studied the performance of ultrasound emulsification with that of classical mechanical agitation. Coarse emulsion prepared by classical mechanical agitation, without being subjected for ultrasonic emulsification) exhibited phase separation within 2 hrs of preparation. Hence we conclude that emulsification time had a direct relation with the stability of nanoemulsion, which was due to the size reduction by ultrasound.