CHOLESTEROL OXIDATION IN MEAT FROM CHICKENS FED ALPHA-TOCOPHEROL-SUPPLEMENTED AND BETA-CAROTENE-SUPPLEMENTED DIETS WITH DIFFERENT UNSATURATION GRADES

The production of B-ring and side-chain oxysterols was evaluated in me at from chickens fed diets differing by the kind of oil or fat added. The effect of supplementary levels of natural antioxidants, as alpha-t ocopherol and beta-carotene, on the meat cholesterol oxidative stabili ty was also studied. Lard, sunflower and olive oil were used as dietar y fat. Raw and cooked meats were analyzed for oxysterols, and choleste rol was also quantified. Oxysterol analyses were carried out by combin ing the use of solid-phase extraction, thin-layer chromatography, capi llary gas chromatography, and capillary gas chromatography-mass spectr ometry. Oxysterols were detected within the 0.1-0.5 mu g/g range in ra w meat. Cooking increased the oxysterol content of the meat, and level s as high as 5 mu g/g muscle tissue were observed. B-Ring oxysterols w ere mainly produced: the alpha- and the beta-epoxycholesterols, the 7 alpha- and 7 beta hydroxycholesterols, and the 7-ketocholesterol. The results showed that the meat from the chickens fed the olive oil-based diet containing alpha-tocopherol at 200 mg/kg of diet presented the b est cholesterol oxidative stability. A positive effect could not be fo und for dietary beta-carotene administered at levels of 15 and 50 mg/k g of diet. Furthermore, a significant decrease in the tissue cholester ol content was observed with the olive and the sunflower oil-based die ts.