The effect of selected antioxidants on the stability of pomegranate seed oil

Pomegranate seed oil (PSO) is a valuable source of bioactive compounds with health-promoting properties, but it is particularly susceptible to oxidation due to its high content of polyunsaturated fatty acids (PUFAs). Oxidative stability is one of the most important indicators of the quality and shelf life of edible oils. A common strategy to enhance oil stability is the application of antioxidants, which can effectively inhibit or slow down oxidative degradation.

In this study, the effects of a plant-derived antioxidant-rich extract (rosemary extract) and a synthetic antioxidant (butylhydroxytoluene, BHT) on the stability of PSO were investigated. The oxidation process was monitored to asses oil quality and stability using parameters such as peroxide value (PV), oxidation induction time (τ₀), and the time corresponding to the maximum oxidative changes (τ_max). The samples were stored for two months at room temperature, in the absence of light, and under refrigerated conditions.

In the first stage of the study, the fatty acid (FA) composition of PSO was determined via gas chromatography. During storage, changes in the oxidative stability of all prepared samples were monitored via pressure differential scanning calorimetry (PDSC), and changes in PV were measured via potentiometric titration.

PSO was characterized by a high content of polyunsaturated FAs (~82%), particularly punicic acid (~74.6%), and exhibited very low oxidative stability, as evidenced by its short τ₀ at 120°C (3.90 min). The addition of both antioxidants had a beneficial effect on PSO stability, which was reflected in the values of τ_0, τ_max, and PV. The natural antioxidant proved to be more effective in this regard, particularly at room temperature.