The impact of oil type on the physical and oxidative stability of oil-in-water nanoemulsions: A comparative study of palm, olive, soybean, and flaxseed oils

The oxidation of the oil phase in oil-in-water nanoemulsions affects both their sensory properties and potential toxicity. This study aimed to investigate the influence of oil type (palm, extra virigin olive, soybean, and flaxseed) on the physical and oxidative stability of nanoemulsions. Additionally, the oxidative stability of these oils was compared in both emulsified and bulk forms. All nanoemulsions formulated with the selected oils exhibited good physical stability. The oxidative stability of the oils, in both bulk and emulsified forms descending order: flaxseed < soybean ≈ olive < palm. However, a significant difference was observed between the oxidative stability of the oils in bulk and emulsified states (p < 0.05). Soybean and flaxseed oils showed greater oxidative stability in nanoemulsified form compared to their bulk counterparts, whereas the opposite trend was observed for palm and olive oils. Reducing droplet size in nanoemulsions containing polyunsaturated, saturated, and monounsaturated fatty acids, respectively, either increased or decreased oxidative stability compared to bulk oils. The findings suggest that optimizing the type of oil and processing temperature can improve the formulation of food products based on nanoemulsions.