Pomegranate seed oil nanoemulsion enriched by α-tocopherol; the effect of environmental stresses and long-term storage on its physicochemical properties and oxidation stability

In this study, pomegranate seed oil (PSO) nanoemulsions loading different amounts of α-tocopherol (0–40%) were produced. The nanoemulsions were fabricated by ultra-sonication method and the influence of thermal treatment (20–90 ◦C), pH (2–8) and ionic strength (0–500 mM NaCl) were investigated on physicochemical properties of all treatments. Moreover, the oxidative stability and α-tocopherol degradation were also assessed on optimal enriched nanoemulsion formulation during 50-day storage. The droplet diameter, viscosity, antioxidant activity, encapsulation efficiency and loading capacity of optimal formulation were 37.5 nm, 514 cp, 92%, 3.45% and 92.5%, respectively. The peroxide value changed in the range of 4.5–5.3 and 6.7–10.5 meq O2/kg in loaded and unloaded nanoemulsions, respectively. Transmission electron microscopy demonstrated spherical morphology of nanoemulsion droplets with diameter average of 40 nm. This study suggested that PSO nanoemulsion loading α-tocopherol could be introduced as delivery system with favorable features under severe environmental conditions.