Food-grade microemulsions and nanoemulsions: Role of oil phase composition on formation and stability

Lemon oil is widely used as a flavoring component in beverages, foods, cosmetics, and household products. Lemon oil comes in a variety of chemical compositions depending on its biological origin, extraction methods, and purification procedures. At present, there is a relatively poor understanding of the influence of lemon oil composition on its functional properties. In this study, we examined the influence of lemon oil fold (1×, 3×, 5× and 10×) on the formation and properties of oil-in-water microemulsions and nanoemulsions. The concentration of both polar (high water solubility and low log P) and non-polar (low-water solubility and high log P) components increased with increasing oil fold. The nature of the colloid dispersions formed was established using an emulsion titration method that involved titrating lemon oil droplets into a surfactant micelle solution (1% Tween 80). Oil fold affected the rate and extent of solubilization, as well as the stability of lemon oil droplets to growth. The maximum amount of lemon oil that could be solubilized within the micelles increased with increasing oil fold, as did the stability of lemon oil droplets to growth. The results were interpreted in terms of the ability of different lemon oil molecules to be incorporated within water or surfactant micelles, and the influence of lemon oil polarity on Ostwald ripening. This study provides valuable information about the relationship between lemon oil composition and its performance in colloidal delivery systems suitable for use in the food and beverage industries.