A new approach for extension of the identification period of irradiated cellulose-containing foodstuffs by EPR spectroscopy

We report on the possibility of identification by EPR spectroscopy of some irradiated cellulose-containing foodstuffs, at a relatively long time after the irradiation, when the characteristic EPR spectral lines of the cellulo se free radical have essentially disappeared. In such cases rather expensiv e and time-consuming methods (e.g. thermoluminescence analysis) have to be applied. The present communication demonstrates with some pre-irradiated sp ices, dried medicinal and sweet herbs that simply heating the samples to 60 degrees C for one hour leads to a significant (50% or more) decrease of th e EPR intensity of the remaining central line of the samples. For compariso n, the loss in the intensity of the same line upon heating non-irradiated s amples at 60 degrees C for one hour was only about 10%. This inexpensive ne w procedure will extend the post-irradiation period in which EPR can be use d for distinguishing irradiated from non-irradiated samples, of certain cel lulose-containing foodstuffs. (C) 2000 Elsevier Science Ltd. All rights res erved.