Detection of Irradiated Tubers (Ginger and Potato) Using Photostimulated Luminescence Technique (PSL)

Photo-stimulated luminescence (PSL) measurement was conducted to detect irradiated gingers (Zingiber officinale Roscoe) and potatoes (Solanum tuberosum) after dark storage for 1 week, 3 and 6 months. Using screening and calibrated PSL, all the samples were correctly distinguished between non-irradiated and irradiated samples at doses 50, 150 and 500 Gy based on photon count values. The PSL signal stability of irradiated samples (150 and 500 Gy) appeared to fade upon 6 months storage but remained well above upper threshold values of 5000 photon counts/ 60 s (PCs) for irradiated gingers and potatoes. The PCs of irradiated tubers showed a general trend of increase with the increase in doses up to 500 Gy. Samples showed highest intensity after irradiation. The differences in intensity to irradiation are possibly attributed to the varying quantity and quality of silicate minerals present in each tuber sample. Tubers irradiated at doses higher than 150 Gy, showed sensitivity index ratio of less than 10. Sensitivity Index was suggested for irradiated samples at doses slightly above 150 Gy. Irradiated samples at doses less than 150 Gy should be subjected for further investigation using thermoluminescence (TL) analysis. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated tubers. (author)