Formation of cholesterol oxides in irradiated raw and cooked chicken meat during storage

The objective of this study was to determine the effect of electron-beam ir radiation on the oxidation of cholesterol in raw and cooked chicken meats w ith different packaging and storage times. Patties were prepared with skinl ess chicken breasts and legs, Half of the patties were used for raw meat st udy and the other half for cooked meat work. For cooked samples, patties we re cooked in an electric oven to an internal temperature of 70 C. Raw and c ooked meat patties were either aerobically or vacuum-packaged before irradi ation. Irradiated patties were stored at 4 C up to 2 wk, and the amounts of cholesterol oxides in the patties were analyzed at 0, 7, and 14 d of stora ge. In raw chicken meat with vacuum packaging, 7 beta -hydroxycholesterol a nd beta -epoxide were the only two cholesterol oxides present in significan t amounts. In raw chicken meat with aerobic packaging, 7 alpha -hydroxychol esterol and 7-ketocholesterol, which were not detected in vacuum-packaged r aw chicken meat, were found. 7 beta -Hydroxycholesterol in raw chicken meat was increased by irradiation and storage time, regardless of packaging. Th e kinds of cholesterol oxides found in cooked meat were basically the same as those found in raw chicken, but the levels in cooked meats at all storag e time were higher than those of the raw meats. With vacuum packaging, irra diation had no consistent effect on the amount of beta -epoxide, 7 alpha -h ydroxycholesterol, or 7-ketocholesterol, but storage significantly influenc ed the amount of 7-ketocholesterol, 7 beta -hydroxycholesterol, and total c holesterol oxides in cooked chicken meat. With aerobic packaging, irradiati on significantly increased the formation of 7 alpha -hydroxycholesterol, 7 beta -hydroxycholesterol, and 7-ketocholesterol in cooked meat stored for 0 and 7 d. After 14 d of storage, however, irradiation had minor effects on the formation of cholesterol oxides in aerobically packaged cooked chicken.