Immediate effects of ionizing radiation on the structure of unfrozen bovine muscle tissue

To measure the immediate changes in the ultrastrcucture of meat induced by ionizing radiation, bovine longissimus dorsi muscle was irradiated with (137) Cs 72 h after slaughter. The temperature of the samples during irradiation was maintained between 0 and 4°C to avoid cellular changes caused by freeze/thaw. Muscle was irradiated at 5, 10, 30 and 50 kGy. At low levels (up to 10 kGy) of radiation, changes in muscle structure were minimal. At levels above 30 kGy major increases in myofibril fragmentation and decreases in the tensile strength of raw and cooked muscles were noted. SDS gel electrophoresis indicated a decrease in myosin. No changes in the ultrastructure were observed using transmission electron microscopy.