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This paper reports the results of a study carried out to verify the applicability of the EN 1787 method, which uses the Electron Spin Resonance (ESR) technique for the identification of irradiated plant-origin foods with health benefits. The method was tested on samples of herbal ingredients of Plant Food Supplements (PFSs), nuts and fresh blueberries. Untreated and irradiated samples of Camellia sinensis (leaves) Ginkgo biloba (leaves), Glycine max (seeds), Silybum marianum (fruits), Vaccinium myrtillus (fruits), almonds, hazelnuts, peanuts, pistachios, walnuts and fresh blueberries were analysed. The work includes an inter-laboratory blind test involving five Italian laboratories that perform routine analyses for the official control of irradiated food. A total of 180 untreated and irradiated samples of PFS ingredients, nuts and fresh blueberries were analysed. The analyses on the irradiated samples were replicated even a long time after irradiation (up to two years depending on the matrix) to test the reliability of the method throughout the shelf life of the products. The results were matrix-dependent: all the 5 kGy irradiated nuts and the 1 kGy-irradiated blueberries were correctly classified, whereas herbal ingredients showed complex ESR spectra with spurious signals which often prevented the correct classification of the sample.