Identification of different irradiated foods containing cellulose, sugars, or bone is possible using electron spin resonance (ESR) spectroscopy. In the present study, ESR spectral characteristics of radiation-induced radicals in irradiated standard materials (cellulose, sugars, and hydroxyapatite) were compared using different ESR spectrometers, such as JES-300 (JEOL, Japan), Miniscope MS-400 (Magnettech, Germany), and $e-scan^{TM}$ Food analyzer (Bruker, USA). Upon irradiation (0-10 kGy), all standard materials showed typical radiation-specific ESR spectra. Instrumental variations in signal intensity, spectral shapes, and detection applicability were observed and should be taken into consideration from practical point of view.