Effect of Drying Treatment on Physical Identification Characteristics of Irradiated Seasonings

The effect of different drying treatments such as spray drying and vacuum drying on the sensitivity of physical detection methods (photostimulated luminescence (PSL), electron spin resonance (ESR), and thermoluminescence (TL)) was investigated for four types of irradiated seasonings. The slurry feed of each seasoning was exposed to γ-ray irradiation at doses of 0, 5, 10 kGy before being subjected to drying process. Spray drying was applied to beef and soybean seasoning while garlic and broth seasoning were exposed to vacuum drying according to routine protocols adopted in the industry. The samples were analyzed by PSL as a rapid screening method followed by validated methods including ESR spectroscopy and TL analysis. The PSL photon counts drastically dropped in all irradiated samples after both drying processes. No ESR signal was obtained from any of the irradiated seasonings before or after the drying applications. All the irradiated seasoning samples produced typical TL glow curves between the specific temperature range of 150-250 °C. However, the shape, peak, and intensity of TL glow curves were greatly affected particularly after the spray drying treatment. In conclusion, the dry treatment can significantly affect the irradiation detection characteristics in seasoning samples.