Oxidation in fish oil-enriched mayonnaise: 4. Effect of tocopherol concentration on oxidative deterioration

Abstract

The effect of the water-dispersible tocopherol preparation, Grindox 1032, and the oil-soluble tocopherol preparation, Toco 70, on oxidative stability in fish oil-enriched mayonnaise was examined. The two commercial antioxidant preparations were supplemented in different levels corresponding to 20–280 ppm tocopherol in addition to the 600 ppm present in the oils used for the mayonnaise. The oxidative stability was assessed by sensory analysis, the tendency of formation of free radicals, and concentrations of lipid hydroperoxides and volatile oxidation products. The effect of tocopherol on oxidation depended on the nature and the concentration of the tocopherol preparation employed, and it also depended on the parameters evaluated. Addition of high levels of Grindox 1032 (∼140–280 ppm tocopherol) thus decreased the intensity of rancid off-flavor, but increased the formation of fishy off-flavors, the tendency of free radical formation and the concentration of certain volatiles. In contrast, low levels of Grindox 1032 (<70 ppm tocopherol) reduced the concentration of some volatiles, but did not seem to influence the off-flavor profile of the mayonnaise. Toco 70, which was only supplemented in low levels (<40 ppm tocopherol) increased the tendency for free radical formation, changed the profile of volatiles, and did not have a clear effect on the fishy and rancid off-flavor formation. Thus, additional tocopherol did not appear to be an efficient antioxidant in fish oil-enriched mayonnaise, perhaps because it cannot prevent the metal-catalyzed decomposition of peroxides, which we previously suggested to play an important role in mayonnaise.