Thermoluminescence of foods: origins and implications for detecting irradiation

Thermoluminescence is one of a number of phenomena being investigated in the U.K. to develop methods for identifying irradiated foods. A survey of the whole sample TL response of over 161 irradiated herbs and spices confirms that signals can be detected, but illustrates the highly variable nature of the response. Roughly 95% of irradiated samples can be correctly identified using such simple measurements. The origins of the TL signals from samples of this type were investigated and found to be due to extraneous inorganic matter, often at extremely low levels. Procedures for using enriched separated material have been established which can distinguish irradiated samples without ambiguity. The method can also be applied to vegetables and fruits. (author)