The Stability of the Virgin Olive and Pumpkin Seed Oils in terms of the Polar Compounds Composition Determined by High-Performance Size-Exclusion Chromatography (HPSEC)

The chemical characteristics and oxidative stability of virgin olive (VOO) and pumpkin seed (PSO) oils during heating at 180 °C were investigated. The oxidative stability was assessed by measuring the rate of changes in total polar compounds (TPC) content and polar fractions including triglyceride polymers (TGP), triglyceride dimers (TGD), oxidized triglycerides monomers (oxTGM), diglycerides (DG), and free fatty acids (FFA). The TPC compositions were analyzed by high-performance size-exclusion chromatography (HPSEC). The VOO had a higher level of oleic acid (62.17 vs. 38.42) while the PSO characterized by its higher level of linoleic acid (39.83 vs. 20.05). The VOO presented a higher ratio of unsaturated to saturated fatty acids than the PSO (5.37 vs. 4.17). The PSO showed significantly higher amounts of the FFA and peroxide value (0.39 % and 10.85 meq/kg, respectively) than the VOO (0.18 % and 6.89 meq/kg, respectively). The PSO contained a higher level of the antioxidative compounds including total tocopherols (725 vs. 585 mg/kg) and phenolics contents (66.27 vs. 25.67 mg/kg) than the VOO. Comparing the results of TPC contents and their compositions during the heating process indicated that the VOO underwent more degradation than the PSO.