Ostwald Ripening Rate of Orange Oil Emulsions: Effects of Molecular Structure of Emulsifiers and Their Oil Composition.

Ostwald ripening, one of the frequently observed instability of flavor oil emulsions, can be easily prevented by adding triacylglycerols to the oil phase. The effect of interfacial characteristics of the emulsion droplets (particularly thickness) on the effectiveness of triacylglycerol inhibition of Ostwald ripening was evaluated in this study. The prepared emulsions were stabilized with emulsifiers with different-size hydrophilic groups, which correlate to droplet interfacial thickness. Emulsions with an oil phase of pure orange oil were unstable due to Ostwald ripening. Modifying the oil phase by adding corn oil or medium-chain triacylglycerol (MCT) effectively inhibited droplet growth. Thicker and less dense droplet surfaces in the emulsions required more triacylglycerol, regardless of its type, to resist Ostwald ripening. When the oil phase contained the same amounts of triacylglycerols, MCT was more effective at inhibiting Ostwald ripening than corn oil. Compared with corn oil, MCT more effectively inhibited Ostwald ripening of the emulsions containing micelles. PRACTICAL APPLICATIONS: When food and beverage industries produce food products containing flavor or essential oils vulnerable to Ostwald ripening as emulsion forms, the findings in this work could provide useful information on the interfacial engineering of emulsions and on how to modify the oil compositions of emulsions using triacylglycerols to improve the stability of these emulsions against Ostwald ripening.