Prevention of Ostwald ripening in orange oil emulsions: Impact of surfactant type and Ostwald ripening inhibitor type

Abstract

The Ostwald ripening phenomenon, an instability observed in essential oil emulsions, could be controlled by modifying the oil composition. Herein, this study evaluated what types of triglycerides used to modify the oil composition may be more effective in inhibiting Ostwald ripening, and also determined how the interfacial properties of the emulsions affected the efficacy of triglycerides in inhibiting Ostwald ripening. Emulsions were stabilized by emulsifiers with differently sized hydrophilic groups, which correlate to the thickness of the interfacial region, and their oil compositions were varied by mixing triglycerides. Significant increase in droplet size was observed in emulsions prepared using only orange oil during storage. Modifying oil composition by adding medium-chain triglycerides (MCT) or long-chain triglycerides (LCT; corn oil in this study) inhibited droplet growth, and adding triglycerides over 20% into the oil phase prohibited Ostwald ripening. LCT was less efficacious in inhibiting Ostwald ripening than MCT for the same content.