EFFECTS OF STORAGE AND VARIOUS INTRINSIC VITAMIN-E CONCENTRATIONS ON LIPID OXIDATION IN DRIED EGG POWDERS

Supplementing the diets of laying hens with 0, 25, 50, 75, 100, and 20 0 mg of all-rac-alpha-tocopheryl acetate (vitamin E) per kg of feed in creased the concentration of this antioxidant in the eggs in a dose-de pendent manner. Storage of spray-dried whole-egg powders at ambient te mperature for up to 18 months resulted in gradual losses of vitamin E after 6 months, with the greatest losses occurring in those powders wi th the highest initial content. Marked changes in the concentration of products of lipid peroxidation (thiobarbituric acid reactive substanc es (TBARS), free fatty acids, oxidised fatty acids, peroxide values, o xysterols) occurred during the storage period which generally correlat ed inversely with the vitamin E content of the powder. The appearance, and sometimes disappearance, of the products with storage time varied with the individual product. Oxidised fatty acids appeared at 0-2 mon ths, free fatty acids at 4-8 months and TBARS at 8-12 months. 25-Hydro xycholesterol and cholestan-3,5,6-triol appeared at 2 months, peaked b etween 4 and 6 months and disappeared by 8 months. 7beta-Hydroxycholes terol, 7-ketocholesterol and cholesterol-5,6-epoxide appeared at 4 mon ths, peaked at 8-12- months and markedly declined by 18 months. Ingest ion of certain lipid peroxidation products, particularly oxysterols wh ich are generally regarded as cytotoxic, could be detrimental to healt h. Methods for preventing oxysterol formation in commercially prepared and stored foods by simply increasing the intrinsic vitamin E concent ration of eggs, which are a major source of cholesterol, would benefit the food industry and human health.