APPLICATION OF PLANT EXTRACTS AND SYNTHETIC ANTIOXIDANTS FOR RAPESEED OIL STABILIZATION

摘要

Antioxidants are used to protect lipids from oxidative deterioration. The substances formed during lipid oxidation are toxic and can cause cancerogenesis and mutagenesis in humans, they also reduce the quality of fat-containing food. Free radicals formed in the course of oxidation initiate chain reactions of peroxide formation (Duch and Yen, 1997; Cuvelier et al., 1996; Dapkevicius et al., 1998; Heinonen et al., 1998). The demand for natural food additives is increasing. Citric acid, ascorbic acid and its ester with palmitic acid are widely used antioxidants in the food industry. Aromatic and spicy plants are considered promising sources for natural antioxidants. In optimizing technological and economical aspects of the application of antioxidants, the possibilities of synergistic action of two or more substances with different mechanisms of lipid stabilization should be explored as much as possible. From this point of view, complex use of such substances as tocopherols, plant extracts (containing carnosic acid and other active compounds), flavonoids (radical scavengers), ascorbates (oxygen quenchers), citric, phosphorous, ascorbic, amino acids and lecitin (synergistic compounds) is of a great interest. The action of synergists in most cases is based on the formation of metalcomplexes or in the regeneration of other antioxidants, by donating them the hydrogen atom. It is assumed that vitamin E is the main plant oil antioxidant in vivo. The radical of tocopherol is regenerated by vitamin C. Possible interactions between ascorbic acid and tocopherol were studied in various food systems (Lambelet et al., 1985). Studies of the effect of these two compounds in oxidized poultry fat demonstrated that α-tocopherol radicals were suppressed by ascorbyl palmitate and consequently the radicals of the latter compound were formed. Measurement of ascorbyl palmitate and a-tocopherol concentrations during the oxidation showed that ascorbyl palmitate was consumed faster, thus suggesting that a-tocopherol was regenerated.