M. Kruszewski3, K. Malec-Czechowska1, A. M. Dancewicz2, T. Iwanenko3, Z. Szot2, M. Wojewodzka3
1 Institute of Nuclear Chemistry and Technology, Pilot Plant for Food Irradiation, Warsaw- Wlochy,
2 Laboratory of Identification of Irradiated Food, Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland,
3 Department of Radiobiology and Health Protection, Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland
Radiation induces damage to the DNA. This damage (fragmentation) can be assessed in the irradiated food using Single Cell Gel Electrophoresis (SCGE), known as DNA comet assay. Fragmentation of DNA may also be caused by improper storage of meat and repeated freezing and thawing. This makes identification of irradiated meat by this assay not reliable enough. In order to know the scale of the processes imitating irradiation effects in DNA of the comets, their shape and lenghts were examined in both unirradiated and irradiated fresh meat (D = 1.5 or 3.0 kGy) stored at 4°C or frozen (-21°) up to 5 months. Comets formed upon SCGE were stained with DAPI or silver and examined in fluorescent or light microscope. They were divided arbitrarily into 4 classes. Comets of class IV were found quite often in fresh meat stored at 4°C. In meat samples that were irradiated and stored frozen, comets of class, I, II and III were observed. The negative comet test is univocal. Positive comet test, however, needs confirmation. The meat should be subjected to further analysis with other validated methods.