Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds

Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds 1 first-author 2 2 2 2 Institute of Atomic Energy Application, Jiangsu Academy of Agricultural Sciences (JAAS), Nanjing 210014, China; Institute of Atomic Energy Application, Jiangsu Academy of Agricultural Sciences (JAAS), Nanjing 210014, China; Food Safety Research, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA Food Safety Research, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA A kind of alfalfa seeds was irradiated by 1, 2, 3, 4 and 5kGy at a dose rate of 6.288kGy·h 1 in a self-shielded irradiator of 137 Cs gamma rays. The EPR spectra, which were measured subsequently between 0.3401 and 0.3501T, showed that there was a direct proportional relationship between the EPR signal strength of free radicals produced by gamma irradiation in the alfalfa seeds and absorbed dose. The first derivative EPR spectra of the alfalfa seeds were very clear and easy to identify. However, the EPR signal strength of the peak-to-peak amplitude decreased rapidly and most of them decayed beyond 50% within 3 days after the seeds were irradiated. It tended to stabilize after half a month since the seeds were irradiated. The differences of the EPR signal strength between the irradiated and unirradiated alfalfa seeds still remained. All seeds were stored at ambient temperature for more than 3 months. Therefore, using EPR spectrometry technique to measure free radicals in alfalfa seeds as a means to determine whether the seeds have been irradiated or not is feasible, relatively fast and simple. Alfalfa seeds EPR spectrum Free radicals Gamma irradiation Detection References Beuchat L R . Int. J. Food Microbiology . 1997 , 34 , 329 - 333 . Int. J. Food Microbiology Ramakrishna N , Lacey J , Smith J E . Int. J. Food Microbiology . 1991 , 13 : 47 - 54 . Int. J. Food Microbiology Hunter C. R ., Hutton D. R. , Troup G . J. ANIAAS . 1988 , 19 ( 4 ): 198 - 199 . J. ANIAAS E 1607-94 practice for use of the alanine-EPR dosimetry system . ASTM Dosimetry Standards for Radiation processing . E 1607-94 practice for use of the alanine-EPR dosimetry system Desrosiers M F , McLaughlin W L . Radiat. Phys. Chem . 1989 , 34 ( 6 ): 895 - 898 . Radiat. Phys. Chem 10.1016/S1001-8042(06)60017-1 S124 + .1,O657.2 2005-10-24 2006-04-20 2021-01-19 2006 Nuclear Science and Techniques 02 17