Challenges associated in stability of food grade nanoemulsions.

Food grade nanoemulsions are being increasingly used in the food sector for their physico-chemical
properties towards efficient encapsulation, entrapment of bioactive compounds, solubilization, targeted
delivery, and bioavailability. Nanoemulsions are considered as one of the important vehicles for the
sustained release of food bioactive compounds due to their smaller size (nm), increased surface area, and
unique morphological characteristics. Nanoemulsification is an ideal technique for fabricating the
bioactive compounds in a nano form. Formation and stabilization of nanoemulsion depends on the physicochemical
characteristics of its constituents including oil phase, aqueous phase, and emulsifiers. This
review is mainly focused on the instability mechanisms of nanoemulsion such as flocculation, Ostwald
ripening, creaming, phase separation, coalescence, and sedimentation. Further, the major factors
associated with these instability mechanisms like ionic strength, temperature, solubilization, particle size
distribution, particle charge, pH strength, acid stability, and heat treatment are also discussed. Finally,
safety issues of food grade nanoemulsions are highlighted.