Food irradiation is the use of high energy ionising radiation to extend shelf life by reducing the bacterial loads associated with natural foods. The University of Glasgow has developed methods and equipment for screening foodstuffs for irradiation.
The pulsed photo stimulated luminescence system was designed and developed at the Scottish Universities Research and Reactor Centre, and provides an opportunity for effective detection of irradiated foods using a rapid instrumental method. Originally developed for rapid screening of irradiated herbs, spices and seasonings, it has been validated for a wider range of foodstuffs and is finding other scientific applications in assessment of fire damaged structures, and environmental dosimetry.
During the measurements the sample is stimulated with a pulsed Infra-Red (IR) source, and UV-VIS Anti-Stokes Luminescence is measured with exceptional sensitivity using a patented digital lock-in photon counting method. Irradiated samples produce a specific signal which is detected and quantified.
For screening, the signal level is compared with two thresholds defined from reference data. The majority of irradiated samples produce a strong signal above the high threshold level. Signals below the lower threshold indicate that the samples have not been irradiated. Intermediate signal levels between the two thresholds suggest that further tests or investigations should be made.