Can irradiation of spices be detected by chemiluminescence?

Chemiluminescence (CL) has been reported as a reliable identification measure for radiation processed spices. Luminescence intensities, however, vary considerably from one spice to another. Even for one spice from various producers, different results have been obtained. One of the main drawbacks of CL is its poor reproducibility. Attempts to reduce the variability have so far been unsuccessful. Since the CL response is frequently a non-monotone function of dose, the applied radiation dose cannot be estimated unequivocally. Attempts to establish an internal standard were not successful. A further hindrance for dose estimation is the fading of luminescence with storage time. In the case of juniper berries 50-78% of the irradiated samples could be identified correctly, depending on selection criteria. With marjoram, however, only one out of five samples could be identified. Variations in the radiation conditions did not change CL. However, an increase in CL was also noted in some experiments with fumigated spices. The CL measurement as a single tool for identifying radiation processed spices seems at the moment not to fulfil the requirements of reliable detection. A combination of methods may eventually allow identification of irradiated spices. (orig./MG)