Ascorbyl Palmitate, γ-Tocopherol, and EDTA Affect Lipid Oxidation in Fish Oil Enriched Salad Dressing Differently

The aim of the study was to investigate the ability of gamma-tocopherol, ethylenediaminetetraacetate (EDTA), and ascorbyl palmitate to protect fish oil enriched salad dressing against oxidation during a 6 week storage period at room temperature. The lipid-soluble gamma-tocopherol (220 and 880 microg g-1 of fish oil) reduced lipid oxidation during storage by partly retarding the formation of lipid hydroperoxides (PV) and by decreasing the concentrations of individual volatile oxidation products by 34-39 and 42-66%, respectively. EDTA (10 and 50 microg g-1 of dressing) was the most efficient single antioxidant, and overall peroxide values and volatiles were reduced by approximately 70 and 77-86%, respectively. Conversely, prooxidant effects were observed with a high concentration of ascorbyl palmitate (300 microg g-1 of fish oil), whereas a low concentration was slightly antioxidative (50 microg/g of fish oil). Finally, a combination of all three antioxidants completely inhibited oxidation during storage, indicating that the prooxidant effects of ascorbyl palmitate were reverted or overshadowed by EDTA and gamma-tocopherol.