Impact of Ultrasonication on the Oxidative Stability of Oil-in-Water Nanoemulsions: Investigations into Kinetics and Strategies to Control Lipid Oxidation

Ultrasonication has emerged as a promising and effective technique for generating nanoscale oil-in-water (O/W) emulsions, offering enhanced physical stability and superior encapsulation activity for various bioactive molecules. Despite its numerous advantages, the impact of the chemical effects of ultrasonic cavitation on the chemical (oxidative) stability of O/W emulsions has not been thoroughly investigated. This study focuses on addressing this gap and comprehending the mechanism of lipid oxidation during the ultrasonic emulsification process. To assess the extent of degradation, the peroxide value (PV) was determined under different ultrasonic conditions (power and time) and monitored throughout the storage to elucidate the kinetics involved. The results indicated that ultrasonication induced lipid oxidation in the emulsions by generating free radicals, leading to a significant increase in PV during storage, particularly under intense sonication conditions. Further investigations explored effective strategies to inhibit lipid oxidation in emulsions. It was observed that the PV decreased by 89 and 42% by altering the emulsifier and oil, respectively. Additionally, incorporating an antioxidant resulted in a 17% decrease in PV. In conclusion, for ultrasonically prepared emulsions, it is advisable to use emulsifiers based on long-chain molecules to enhance stability and prolong the shelf life of encapsulated materials.