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KMID : 1160620040090030227
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Preventive Nutrition and Food Science
2004 Volume.9 No. 3 p.227 ~ p.231
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Properties of Pulsed Photostimulated Luminescence and Thermoluminescence for Detection of Gamma-Irradiated Teas during Storage
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Kausar Tusneem
Kim Byeong-Keun
Yang Jae-Seung
Byun Myung-Woo
Kwon Joong-Ho
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Abstract
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Green, black and oolong teas were irradiated by (60)^Co-gamma rays (0～10 kGy) and were investigated for detection of irradiation treatment using pulsed photostimulated luminescence (PPSL) and thermoluminescence (TL) during storage. Teas irradiated at 2.5 kGy or more showed a photon count of greater than 5000 counts/60 sec while the non-irradiated yielded only 650～1000 count/60 sec. Correlation coefficients between irradiation dose and photon counts/60 sec were 0.8951, 0.7934 and 0.9007 for green, black and oolong teas, respectively. The TL glow curves for minerals isolated from the non-irradiated teas were situated at about 300℃ with a low intensity, but for irradiated samples were approximately 150℃ with a high intensity. The TL ratios (TL₁/TL₂), calculated from values after initial radiation and then after re-irradiation of the teas, were below 0.1 for the non-irradiated samples and higher than 1.44 for all irradiated samples, enhanced the reliability of the identification results for TL. The signal intensity of PPSL and TL for irradiated teas decreased with the lapse of post-irradiation storage time at room temperature but was still distinguishable from that of the non-irradiated samples even after one year.
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KEYWORD
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teas, irradiation, PSL, TL, storage
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