Food irradiation is used to reduce the health risk associated with food-borne pathogens such as Salmonella and to prolong shelf life (sprout inhibition, delay of ripening). In fact, ionizing radiation inhibits the division of microorganisms and creates so-called radiolytic products as well as free radicals. In a dry environment these radicals are relatively stable.
For example, irradiated poultry bones or dried spices may contain a substantial amount of stable radicals which can be easily detected by EPR spectroscopy (EPR = electron paramagnetic resonance, also known as ESR). Extensive consultations and round-robin tests were conducted during the 1990s in order to set European-wide standards for sample preparation, measurement protocol and unequivocal identification of irradiated food via EPR.Currently three EU norms exist, defining food irradiation control via EPR spectroscopy.