Antioxidant effect of soy lecithins on vegetable oil stability and their synergism with tocopherols

The antioxidant effect of lecithins was tested on several oils and fats varying in FA composition and tocopherol content. Standard lecithins, when added at a level of 1% w/w, exhibited a good protective effect against oxidation. This effect was observed to depend on the phospholipid content of the tested lecithins and the FA composition of the tested oils. Better results were obtained with lecithin samples containing high proportions of PC and PE. Indeed, the main antioxidant mechanism of lecithins was due to a synergistic effect between amino-alcohol phospholipids and gamma- and delta-tocopherols. No synergism was observed with alpha-tocopherols, especially when the tested oil was rich in linoleic acid. Therefore, the antioxidant protection of lecithins was not effective for sunflower oil. Finally, the use of fractionated or enriched lecithins was not clearly advantageous compared to standard oil lecithins.