Preparation of O/W and W/O Nanoemulsions Based on Olive Oil and Investigation of Its Physicochemical Properties and Oxidative Stability

In this study, the oxidative and physicochemical stability of Oil/Water (O/W) and Water/Oil (W/O) nanoemulsions, extra virgin olive oil, and oleic acid were investigated. Nanoemulsions were prepared using a HPH technique. Then, the test of particle size, PDI, zeta potential, viscosity, refractive index, storage stability, pH, PV, conjugated dienes va1ue, and TBA index was performed. The particle size in all studied nanoemulsion samples was less than 200 nm on the first day. With increasing time, particle size, zeta potential, and PDI increased, but pH decreased. The viscosity of W/O nanoemulsions was higher than O/W types. Also, the present study showed that the PV, TBA, and conjugated dienes value and refractive index increased significantly in all samples with the increase in the incubation duration. In terms of physical stability, it was found that O/W nanoemulsion samples are more stable than W/O. Also, compared to oil samples, nanoemulsion samples entered the final oxidation phase later, and types of O/W nanoemulsions have more physical stability than W/O nanoemulsions.