THE EFFECTS OF DIETARY ALPHA-TOCOPHEROL AND SURFACE APPLICATION OF OLEORESIN ROSEMARY ON LIPID OXIDATION AND CHOLESTEROL OXIDE FORMATION INCOOKED RAINBOW-TROUT (ONCORHYNCHUS-MYKISS) MUSCLE

The inhibitory effect of dietary a-tocopherol supplementation (100 and 500 mg alpha-tocopheryl acetate/kg diet) and an oleoresin rosemary di p on lipid and cholesterol oxidation in cooked rainbow trout (Oncorhyn chus mykiss) during storage at 4C for 48 h war; investigated. The 2-th iobarbituric acid-reactive substances (TBARS) values of cooked fish mu scle increased during storage for all treatments. Dietary alpha-tocoph erol supplementation partially inhibited lipid oxidation. Surface appl ication of oleoresin rosemary further enhanced this protective effect. Cholesterol oxides were formed in all the samples following cooking a nd storage. The major cholesterol oxidation products (COPS) were ident ified as 7 beta-hydroxycholesterol, alpha- and beta-epoxides, and 7-ke tocholesterol. Formation of COPS was reduced by dietary supplementatio n with alpha-tocopherol and surface application of oleoresin rosemary. Statistical analysis revealed a highly significant (p<0.01) inhibitor y effect of oleoresin rosemary on COPS formation.