• Food Science and Preservation
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• v.8 no.3
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• pp.291-295
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• 2001

Photostimulated luminescence (PSL) analysis was applied to determine whether some agricultural commodities of Korean and Chinese origins have been irradiated or not. Cereals (brown rice and buckwheat) and legumes (soybean, peanut, fed bean and mung bean) were exposed to gamma irradiation at 0.5 ∼4 kGy The Korean garlic was irradiated at 0.05 ∼0.5 kGy. Cereals and mung bean were tool applicable to the PSL measurement, showing the intermediate values between the lower (700 photon counts, negative) and the upper threshold values (5,000, positive), however PSL values determined for soybean, peanut, red bean and garlic were suitable for being discriminated between nonirradiated and irradiated samples. There was no significant difference in PSL properties accgrding to the sample origins.

• Food Science of Animal Resources
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• v.30 no.2
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• pp.232-235
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• 2010

This study examined the photostimulated luminescence (PSL) detection method suggested by the Korean Food and Drug Administration to assess whether the method can be used to identify irradiated spices in restructured pork patties, which served as a model system for processed meat products. Red and black pepper powders were irradiated at 0, 5.0, 7.5, and 10 kGy, and pork patties were formulated with the spice at irradiated pepper concentrations of 0.1% and 0.5%. PSL was then used to estimate amounts of light derived from the spice itself and pork patties. The results of PSL analysis showed that red and black pepper powders were determined as positive and presumptive positive, respectively, when irradiated at more than 7.5 kGy. However, when used in pork patties, all samples were negative for irradiation. Thus, PSL may not be useful in detecting irradiated ingredients used in processed meat products.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.498-501
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• 1998

It was determined whether photostimulated luminescence (PSL) is applicable to the detection of post-irradiation of foods by measuring PSL photon counts for unirradiated and irradiated pepper powder, dried herbs, fresh shrimp, potato, soybean, dried fig, chestnut, dried squid, and dried cod. The samples were irradiated with $^{60}Co\;{\gamma}-ray$ source and PSL photon counts were measured for them. The photon counts of unirradiated samples were lower than 2,000 for potatoes and less than 1,000 for the others. The photon counts of the irradiated samples except dried figs (0.5 kGy), chestnuts (0.2 kGy), and dried squid (0.5 kGy) were higher than 1,000, and the photon counts increased with dose. Thus, PSL might be applied to the primary detection of irradiated foods.

• Korean Journal of Food Science and Technology
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• v.42 no.2
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• pp.136-141
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• 2010

This study attempted to determine whether Photostimulated Luminescence (PSL) is applicable for the detection of post-irradiated foods by measuring the PSL photon counts of unirradiated and irradiated dried spices and herbs. A total of 19 dried spices and herbs was irradiated with a $^{60}Co$ $\gamma$-ray source at 1, 5 and 10 kGy followed by measurement of PSL photon. The photon counts of unirradiated samples below 700 correspond to negative. Fifteen samples irradiated over 1 kGy showed photon counts of more than 5,000, indicating irradiation treatment. Intermediate counts (photon count 700-5,000) were observed in irradiated white/black pepper, nutmeg and cinnamon bark at 10 kGy. These results suggest that it is possible to detect whether dried spices and herbs were irradiated by analyzing PSL, with the exception of white/black pepper, nutmeg and cinnamon bark. Irradiated white/black pepper, nutmeg and cinnamon bark containing low levels of minerals were not sensitive to PSL. Therefore, further investigation is sugguested to be performed by Thermoluminescence (TL) analysis or another validated or standardized method.

• Food Science and Preservation
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• v.13 no.2
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• pp.211-215
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• 2006

Photostimulated luminescence (PSI) and thermoluminescence (TL) were analyzed for dried vegetables irradiated at 0, 1, 4 and 7 kGy, such as dried oak mushroom, spinach, radish leaves, water cress, radish, and pumpkin, to detect irradiation treatment. PSL results that photon counts for non-irradiated samples were lower than 700 that corresponds to negative, while those of irradiated samples over 1 kGy showed positive photon counts$(\geq5000)$, indicating irradiation treatment Meantime, TL ratio by normalization was lower than 0.021 in threshold value for non-irradiated samples and more than 0.653 for irradiated samples, and therefore it was possible to detect whether the 6 kinds of dried vegetables were irradiated or not by analyzing PSL and TL.

• Journal of Radiation Industry
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• v.2 no.1
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• pp.27-34
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• 2008

Photostimulated luminescence (PSL), electron spin resonance (ESR) and thermoluminescence (TL) analyses were conducted to detect whether 258 kinds of extracted and powdered forms food additives were irradiated or not. In a view of the PSL results, 9 kinds of the extracted and powdered samples (3.2%) showed over 5,000 photon counts $(60sec)^{-1}$ and these samples were judged to be irradiation-positive. Thirty nine kinds of the samples (15.6%) yielded 700~5,000 photon counts $(60sec)^{-1}$ and these samples were grouped into irradiation-potential, while the samples showed below 700 photon counts $(60sec)^{-1}$ sec were judged to be irradiation-negative. TL glow curves for minerals separated from 5 samples were detected at $150^{\circ}C$ with high intensity. However, TL analysis did not apply to other irradiation-positive and irradiation-potential samples because the minerals for TL detection were not separated from the samples. ESR measurements for irradiation-positive and irradiation-potential samples, judged by PSL detection, showed no specific signals to irradiation. The results indicated that PSL could be applied to identify irradiation treatment of extracted and powdered food additives, while TL was optional and ESR was not suitable for detection extracted and powdered food additives.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.374-378
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• 2009

Three physical methods, photostimulated luminescence (PSL), thermoluminescence (TL), and electron spin resonance (ESR), have been applied to detect the irradiation treatment for the non- and steamed sesame seed samples. PSL successfully screened the irradiated samples from the non-irradiated control by comparing their photon counts (PCs) with the lower (less than 700 count/60 sec) and upper threshold values (higher than 5,000 count/60 sec). TL signals were still detected in all irradiated samples even after steaming, which was reconfirmed with TL ratios [integrated area of $TL_1$ (the first glow)/$TL_2$ (the second glow)] through re-irradiation step. ESR spectrometry showed that radiation-induced cellulose radicals were detected in all the irradiated samples irrespective of steaming treatment. Identification of the irradiated sesame seeds was possible even after steaming by analyzing PSL, TL, and ESR.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.343-346
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• 2003

Photoluminescence(PL), photostimulated luminescence(PSL) and thermoluminescence(TL) in $SrC1_2$:$Eu^{2+}$ , $Na^{+}$ phosphor powder were measured, and the activation energies(trap depth) of traps associated with TL and PSL were investigated. The PL and PSL in the studied sample is due to the $4f^{6}$ 5d\longrightarrow$4f^{7}$transition of $Eu^{ 2+}$. TL glow curve is single peak, and its peak temperature is about 377.2 K. The PL, PSL and TL emission spectra of the phosphors are located in the range of 380∼440 nm, peaking at 408 nm. The activation energy of the PSL trapping center is 0.78 eV and that of the TL trapping center is 0.79 eV. We, thus, suggest that the trapping centers giving rise to the PSL are identical to those giving rise to the TL.

• Food Science and Preservation
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• v.13 no.1
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• pp.50-54
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• 2006

The identification characteristics of inadiated dried onion and garlic at 1, 4 and 7 kGy were investigated by analyzing their photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR). The PSL results showed that the photon counts of non-irradiated dried onion were less than 700 (negative) and those of irradiated samples at 1kGy or more were over 5000 (positive), making it possible to discriminate non-irradiated onions from irradiated ones. However, the intermediate counts (700-5000) were observed in irradiated garlic at 1 and 4 kGy, even though positive counts were measured in 7 kGy group. Radiation-induced TL glow curves $(TL_1)$ were measured at $150^{\circ}C$ range in both irradiated onion and garlic samples at 1 kGy or more, which could identify irradiated groups. Furthermore, determination of TL ratios $(TL_1/TL_2)$ for both samples could verify the above results. It was found, however, that ESR spectroscopy was not suitable for the detection of irradiated dried onion and garlic.

• Journal of Ginseng Research
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• v.37 no.4
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• pp.483-490
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• 2013

Gamma-irradiation (0-7 kGy) of ginseng is permitted in Korea for the purpose of microbial decontamination; with strict labeling, traceability and monitoring requirements. An identification study was conducted to determine the photostimulated-luminescence (PSL) and thermoluminescence (TL) properties of gamma-irradiated fresh and white ginsengs cultivated in different areas. Dose- dependent PSL-based screening was possible for white ginseng samples; however, inappropriate results from non-irradiated fresh ginseng samples were obtained, showing intermediate (700 to 5,000) or positive ($T_2$ >5,000, irradiated) PSL counts due to the abundance of minerals on the surfaces of the samples. TL analysis of separated minerals from all non-irradiated samples gave TL glow curves of low intensity with a maximum peak after $300^{\circ}C$. However, well-defined irradiation-specific (high intensity with a maximum peak at about $200^{\circ}C$) glow curves were observed for all the irradiated samples, regardless of their type and origins. TL ratios (first glow curve /second glow curve) were also determined to confirm the irradiated (>0.1) and non-irradiated (<0.1) results. SEM-EDX (scanning electron microscope-energy dispersive X-ray) and XRD (X-ray diffraction) spectroscopic analyses showed that feldspar and quartz minerals were the main source for the typical radiation-specific luminescence properties.