Veselka Gancheva

Identification of irradiation treatment of aromatic herbs, spices and fruits by electron paramagnetic resonance and thermoluminescence.

Electron paramagnetic resonance and thermoluminescence signals induced by gamma irradiation in some herbs, spices and fruits were systematically studied in order to detect the treatment. Using European protocols the validity and effectiveness of these two techniques are compared in regard to time of storage after irradiation.

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 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 degrees 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 degrees 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.

Comparative identification of irradiated herbs by the methods of electron paramagnetic resonance and thermoluminescence

Abstract Non irradiated and γ -irradiated dry herbs savoury ( Savoury ), wild thyme ( Thymus serpollorium ) and marjoram ( Origanum ) with absorbed dose of 8 kGy have been investigated by the methods of elecrtron paramagnetic resonance (EPR) and thermoluminescence (TL). Non-irradiated herbs exhibit only one weak siglet EPR signal whereas in irradiated samples its intensity increase and in addition two satelite lines are recorded. This triplet EPR spectrum is attributed to cellulose free radical generated by irradiation. It has been found that upon keeping the samples under the normal stock conditions the life-time of the cellulose free radical in the examined samples is ∼60–80 days. Thus the conclusion has been made that the presence of the EPR signal of cellulose free radical is unambiguous indication that the sample under study has been irradiated but its absence can not be considered as the opposite evidence. In the case when EPR signal was absent the method of TL has been used to give the final decision about the previous radiation treatment of the sample.

Recent Development of EPR Dosimetry

In the last two decades EPR spectrometry has expanded significantly in the field of practical applications. This is due mainly to the high selectivity and sensitivity of the method. Moreover, it is a non-destructive technique and in some cases samples may be kept as documents for future inspection. The aim of the present chapter is to highlight the current status, as well as the near future trends in development of Solid State/EPR dosimetry. The main subjects considered are the recent developments in SS/EPR dosimetry in standard and emergency accidental cases, identification of irradiated foodstuffs as well as new approaches to the extension of the period of identification by EPR.

Some Recent Developments of EPR Dosimetry

In the last three decades EPR spectrometry has expanded significantly in the field of practical applications. This is mainly due to its high sensitivity (1012–1013 molecules, which means 10–11 to 10–12 M) and selectivity (it can discover “needle in hayrick”). Moreover, it is a non-destructive technique and in some cases samples may be kept as documents for future inspection. The aim of the present chapter is to highlight the current status, as well as the near future trends in development of Solid State /EPR dosimetry. The main subjects considered are the recent developments in SS/EPR dosimetry in standard and emergency accidental cases, identification of irradiated foodstuffs as well as new approaches to the extension of the period of identification by EPR.

Comparative investigation of irradiated meat by the methods of electron paramagnetic resonance and gas chromatography

Abstract A comparative study of irradiated pork meat containing bone was made by the methods of electron paramagnetic resonance (EPR) and gas chromatography (GC). In this investigation EPR has the advantage to be a very fast and unambiguous method even in the cases of thermal treatment of bones. On the other hand, GC analysis is a time consuming procedure however, it becomes very valuable for meat samples that contain no bones.