ABSTRACT
The mechanism of antioxidant activity is the protection of lipid hydroperoxides against their decomposition to free radicals. Lipids contain unsaturated fatty acids, which are oxidized by oxygen in the air into hydroperoxides. Dietary oils, recommended for healthful nutrition, often contain high amounts of polyunsaturated fatty acids. The majority of consumers prefer natural antioxidants, mainly for ideological reasons; the chapter discusses the stabilization of food lipids with natural antioxidants. Mixtures of synthetic and natural antioxidants are sometimes used; identical substances of synthetic nature or antioxidants synthesized by biochemical processes may be applied. All vegetable oils contain tocopherols as antioxidants, at least in small amounts. The antioxidant activity of tocopherols is substantially increased by the addition of ascorbyl palmitate. The tocopherol content of olive oil is low, but both olive fruits and virgin olive oil contain a mixture of other antioxidants, which are derivatives of hydroxytyrosol.
