Detection of Irradiated Chicken, Pork and Beef by ESR Spectroscopy

To identify irradiated foods, studies have been carried out with electron spin resonance (ESR) spectroscopy on bone containing foods, such as chicken, pork, and beef. Bones cleaned, pieced and dried were irradiated with doses of 0, 1, 3, 5 kGys using a irradiator. The bones were placed in a resonant quartz tube with an internal diameter of about 4.0 mm within the Bruker Win-ESR spectrometer, and the intensity of the ESR signal could be quantified by double integration of the first derivative spectrum. The irradiated bone presented an asymmetric absorption in shape, different from that of an unirradiated one. It could be possible to detect at doses lower than 1 kGy below the dose employed commercially (3 kGy) in the case of irradiated chicken bone. The signal intensity was greatest in the beef bone, intermediate in the pork bone and lowest in the chicken bone; it was normally lower for smaller animals than for larger species, and small variations were observed between samples of the same species. The intensity of the signal induced in bones increased linearly with irradiation doses in the range of 1.0 kGy to 5.0 kGy, and it was possible to distinguish between samples given low and high doses of irradiation. The signal stability for 6 weeks made them ideal for the quick and easy identification of irradiated meats.