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A recent FSA survey for irradiated foods found that 42% of dietary supplements sampled were irradiated.
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A dietary supplements manufacturer suggested that pharmaceutical grade talc, used as an excipient in a number of such products, may confound the TL test for irradiation treatment. It was proposed that talc gives a natural geological TL signal in the temperature range used to detect irradiated food.
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The aim of the work is to investigate the luminescence properties of talc to see if talc gives rise to false indication of irradiation treatment using the TL test.
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The work is necessary to establish whether or not there are grounds to consider qualifying or altering the European standardised method for the TL detection of irradiated foods (CEN standard EN1788).
The work involved analysis of authentic source materials which are used to produce pharmaceutical grade talc. The thermal stability of these samples is to be investigated along with the effects of light exposure on both irradiated and non-irradiated samples, and commercially processed materials.
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TL is a procedure for detecting irradiated food which make use of mineral grains that are present in small amounts in many foods . These mineral grains act as dosimeters which, when irradiated, store energy as charge centres trapped within their crystal lattice. When these minerals are exposed to some energy (heat for TL), the stored energy is liberated as the charge centres are released from their energy traps, giving rise to the emission of light that can be measured using sensitive light-detecting instruments.
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Find more about this project and other FSA food safety-related projects at the <a href="http://www.food.gov.uk/science/research/" target="_blank">Food Standards Agency Research webpage</a>.