Low-dose X-ray irradiation of wheat and bean samples detectable by fluorescence excitation spectroscopy (FES)

ABSTRACT Ionizing irradiation is used to preserve foodstuffs and improve food safety, but it is not permitted for organic products, with the exception for using low doses (less than 500 mGy) for detection purposes (e.g. the presence of foreign objects). Analytical verification of irradiation is possible by detection of 2-alkylcyclobutanones (2-ACBs) in products irradiated with 10 Gy or more. Effects of lower doses of radiation on foodstuffs have not been investigated yet, but in blood, irradiation is detectable even at intensities of 1 mGy. The aim of this preliminary study was to determine whether fluorescence excitation spectroscopy (FES), a method which is very sensitive to small changes in the product, could differentiate between bean seeds and wheat grains exposed to X-rays of different intensities. The bean and wheat grain samples were irradiated at 500 mGy (dose limit value for detection purposes), 50 mGy (very low dose) and 0 mGy (control). Measuring the delayed luminescence by FES, effects of irradiation were found in the wheat samples in the FES-parameter Mw1-r, with the highest values for samples irradiated with 500 mGy, intermediate values for 50 mGy and lowest values for 0 mGy (control) (p < 0.001). The effects were less apparent in bean seeds, with a significant difference (p < 0.05) in the parameter Mw1-r only when comparing irradiation at 500 mGy with the control. The parameter differentiating the irradiation intensities was the same for both seeds and changed in the same way. Thus, systematic dose-specific effects were observed for low-dose irradiation intensities.