Identification of red pepper powder irradiated with different types of radiation using luminescence methods: A comparative study.

The purpose of this study was to verify the reliability of photostimulated luminescence (PSL) and thermoluminescence (TL) methods for identifying irradiated foods, described in the European standards EN 13751:2002 and EN 1788:2001, respectively, which were established solely through interlaboratory studies on gamma-irradiated food. Red pepper powder samples irradiated with electron-beams (e-beams), gamma rays and high-energy X-rays were used as model foods. Samples irradiated with each radiation type at ⩾4 kGy could be correctly identified by the PSL method, whereas samples irradiated at ⩾0.5 kGy with each radiation type could be correctly recognized by the TL method when e-beams, gamma rays, or high-energy X-rays were used as normalization sources. However, different TL intensities were observed for minerals separated from red pepper powder for different irradiation sources, which was confirmed using pure quartz and K-feldspar minerals. Further interlaboratory studies are required to verify this phenomenon.

Development of radiation indicators to distinguish between irradiated and non-irradiated herbal medicines using HPLC and GC-MS.

The effects of high dose γ-irradiation on six herbal medicines were investigated using gas chromatography-mass spectrometry (GC/MS) and high-performance liquid chromatography (HPLC). Herbal medicines were irradiated at 0-50 kGy with (60)Co irradiator. HPLC was used to quantify changes of major components including glycyrrhizin, cinnamic acid, poncirin, hesperidin, berberine, and amygdalin in licorice, cinnamon bark, poncirin immature fruit, citrus unshiu peel, coptis rhizome, and apricot kernel. No significant differences were found between gamma-irradiated and non-irradiated samples with regard to the amounts of glycyrrhizin, berberine, and amygdalin. However, the contents of cinnamic acid, poncirin, and hesperidin were increased after irradiation. Volatile compounds were analyzed by GC/MS. The relative proportion of ketone in licorice was diminished after irradiation. The relative amount of hydrocarbons in irradiated cinnamon bark and apricot kernel was higher than that in non-irradiated samples. Therefore, ketone in licorice and hydrocarbons in cinnamon bark and apricot kernel can be considered radiolytic markers. Three unsaturated hydrocarbons, i.e., 1,7,10-hexadecatriene, 6,9-heptadecadiene, and 8-heptadecene, were detected only in apricot kernels irradiated at 25 and 50 kGy. These three hydrocarbons could be used as radiolytic markers to distinguish between irradiated (>25 kGy) and non-irradiated apricot kernels.

Identification of gamma-ray irradiated medicinal herbs using pulsed photostimulated luminescence, thermoluminescence, and electron spin resonance spectroscopy.

Dried herbal samples consisting of root, rhizome, cortex, fruit, peel, flower, spike, ramulus, folium, and whole plant of 20 different medicinal herbs were investigated using pulsed photostimulated luminescence (PPSL), thermoluminescence (TL), and electron spin resonance spectroscopy (ESR) to identify gamma-ray irradiation treatment. Samples were irradiated at 0-50 kGy using a 60Co irradiator. PPSL measurement was applied as a rapid screening method. Control samples of 19 different herbs had photon counts less than the lower threshold value (700 counts 60 s(-1)). The photon counts of non-irradiated clematidis radix and irradiated evodia and gardenia fruits were between the lower and upper threshold values (700-5,000 counts 60 s(-1)). TL ratios, i.e., integrated areas of the first glow (TL1)/the second glow (TL2), were found to be less than 0.1 in all non-irradiated samples and higher than 0.1 in irradiated ones providing definite proof of radiation treatment. ESR spectroscopy was applied as an alternative rapid method. In most of the irradiated samples, mainly radiation-induced cellulosic, sugar, and relatively complicated carbohydrate radical ESR signals were detected. No radiation-specific ESR signal, except one intense singlet, was observed for irradiated scrophularia and scutellaria root and artemisiae argyi folium.

Detection of gamma-irradiated sesame seeds before and after roasting by analyzing photostimulated luminescence, thermoluminescence, and electron spin resonance.

Sesame seeds were irradiated using a (60)Co irradiator (0-4 kGy) and then roasted (220 degrees C for 10 min). To identify the irradiation treatment, physical detection methods like photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR) have been investigated before and after roasting. The photon counts of the irradiated samples (nonroasted and roasted) were higher than those of nonirradiated ones, making it possible to distinguish the two samples. The threshold values of nonroasted and roasted samples increased linearly with the irradiation dose, respectively. The TL for the nonirradiated nonroasted and roasted samples presented a lower peak at about 300 degrees C, but irradiated samples showed a higher peak at around 150 degrees C. The areas of TL glow curves were 15 times higher in nonroasted as compared with roasted samples. TL ratio [integrated area of TL 1 (the first glow)/TL 2 (the second glow)] obtained by the reirradiation step was 0 in nonirradiated samples and more than 0.15 in irradiated samples. The radiation-induced ESR signals originating from cellulose were determined in irradiated samples before and after roasting.

Study of photostimulated- and thermo-luminescence characteristics for detecting irradiated kiwifruit.

Photostimulated luminescence (PSL) and thermo-luminescence (TL) analyses were conducted to detect irradiated kiwifruits. Samples were irradiated with Co-60 gamma-rays at 0-2 kGy. The freeze-dried kiwifruit peel showed 309 photon counts (PCs) for nonirradiated samples that accounted for less than the lower threshold value (700 counts/60 s, negative) and above 9306 PCs for 1 and 2 kGy-irradiated samples, which was higher than the upper threshold value (5000 counts/60 s, positive). However, PSL signals of irradiated samples remarkably decreased after 6 weeks of storage. The TL measurement using minerals isolated from the whole kiwifruit surface revealed a glow curve (TL 1) with a low intensity at 200-300 degrees C in nonirradiated samples but with a higher intensity at around 180 degrees C in irradiated samples at 1 kGy or more. The TL ratios, integrated areas of TL 1/TL 2 that was measured after 1 kGy re-irradiation for the TL 1-tested minerals, were less than 0.1 in nonirradiated samples and higher than 0.1 in irradiated ones and could verify TL 1 results. The inorganic dust minerals used were mainly composed of feldspar and quartz.