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 cellulose free radical have essentially disappeared. In such cases rather expensive and time-consuming methods (e.g. thermoluminescence analysis) have to be applied. The present communication demonstrates with some pre- irradiated spices, dried medicinal and sweet herbs that simply heating the samples to 60°C for one hour leads to a significant (50% or more) decrease of the EPR intensity of the remaining central line of the samples. For comparison, the loss in the intensity of the same line upon heating non- irradiated samples at 60°C for one hour was only about 10%. This inexpensive new procedure will extend the post-irradiation period in which EPR can be used for distinguishing irradiated from non-irradiated samples, of certain cellulose-containing foodstuffs.
Yordanov, N. D., & Gancheva, V. (2000). A new approach for extension of the identification period of irradiated cellulose-containing foodstuffs by EPR spectroscopy. Applied Radiation and Isotopes, 52(2), 195–198. https://doi.org/10.1016/S0969-8043(99)00075-5