• Applied Biological Chemistry
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• v.25 no.4
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• pp.206-210
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• 1982

Effects of pH, organic acides and UV irradiation on the browning of ginseng were investigated. Browning of ginseng tended to increase slightly in the alkaline pH range, whereas no discernible pH effect was observed in the pH ranges of 3.0-5.0 and 10.0-12.5. The treatment of fresh ginseng with organic acid such as citric acid, succinic acid, and tartaric acid greatly enhanced the browning reaction of ginseng but all treatments of mixture of glucose, glutamic acid, and glucose+glutamic acid with fumaric acid decreased the browning reaction except the treatment of fumaric acid only. The addition of ascorbic acid in concentration of greater than 0.1 M markedly accelerated the browning reaction and concurrently increased the red color, a characteristic color of quality red ginseng. Irradiation of ultraviolet light while drying red ginseng increased the brown color intensity in the first 5 days and thereafter decreased the brown color intensity.

• 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.

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.63-68
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• 2011

The aim of this study was 1,4-dioxane's degradation efficiency and toxicity test applying E-beam. The experiments were shows that the degradation efficiency in the initial concentration of 1,4-dioxane and the irradiation capacity of E-beam and the degree of mineralization based on a change of scavenger gas. The biological toxicity test by using on of green algae, Pseudokirchneriella Subcapitata was conducted to lead the reducing toxicity. Degradation efficiency of 1,4-dioxane was improved when E-beam irradiation intensity was higher and the efficiency of TOC removal using Radical scavenger gas was increased by $N_2O$, $O_2$ and $N_2$ in order. In 4 days(96hrs), toxicity test results indicated that toxicity effect was decreased by increase of E-beam irradiation intensity.

• Journal of Korean Society on Water Environment
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• v.38 no.2
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• pp.72-81
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• 2022

Numerous studies have investigated the occurrence and fate of microplastics in the environment; however, only limited effort has been devoted to exploring the characteristics of dissolved organic matter (DOM) leached from microplastics. In microplastic (MP)-contaminated environment, MPs are typically mixed with naturally-occurring particles, which interferes with their detection in the environment. Thus, it is necessary to distinguish between the DOM leached from MPs and those leached from natural particles and also to characterize their properties. This study investigated DOM leaching behavior from MPs (polystyrene: PS, polyvinylchloride: PVC) and natural particulates (forest soil: FS, litter leaves: LL) under light, which is considered one of the main weathering processes that affect MPs in the environment. The leached DOM concentrations and fluorescence characteristics were compared under dark versus light conditions. Regardless of the origins, UV light promoted DOM release from all the particulates. More DOM was released from natural particles than from MPs under both conditions. However, the effect of promoting DOM release by UV was more pronounced for MPs than for natural particles. It was observed from fluorescence spectra that the intensity of the humic-like region was substantially reduced when MP-derived DOM was exposed to UV light, whereas the change of intensity was very little for natural particles. Under light conditions, the ratio of protein-like to humic-like fluorescence of MP-derived DOM was higher than that of DOM from natural particles. This study implies that a substantial amount of DOM could be leached from MPs even in MP-polluted environment under UV irradiation. Protein/humic fluorescence ratio could be utilized as a fast probing indicator to separate the two sources of particles under light.

• Korean Journal of Food Science and Technology
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• v.49 no.6
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• pp.693-698
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• 2017

Turmeric is a yellow food-coloring spice containing curcuminoids, curcumin, demethoxycurcumin (DMC), and bisdemethoxycurcumin (BMC), which have several physiological effects. In the present study, the effect of microwave irradiation on the chemical properties, antioxidant activity, and cytotoxicity of turmeric were investigated. Degradation of turmeric pigments was accelerated upon increase in irradiation time or intensity at 405 nm. Residual levels of curcumin, DMC, and BMC after 5 minutes of irradiation at 700 W were 11.3, 34.4, and 71.2%, respectively. Scavenging activities of turmeric pigment against 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH) peroxyl radical and nitrite were enhanced significantly after microwave radiation. However, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity remained unaffected. Cytotoxic activity of turmeric was significantly reduced, and hydrogen peroxide generated from turmeric increased after microwave irradiation. The results obtained indicate that microwave irradiation affects chemical stability and bioactivity of turmeric pigment. Hence, these effects should be considered when processing foods containing turmeric pigments.

• Food Science and Preservation
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• v.5 no.3
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• pp.199-206
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• 1998

Comparative effects of gamma irradiation and methyl bromide (MBr) fumigation on disinfestation and some physicochemical attributes of acorn seeds were investigated. Insects in domestic acorns were identified to be Curculio dentipes Roelofs and Dichocrocis punctiferalis Guenee, which were easily disinfestated immediately after commercial MBr fumigation. Irradiation also showed similar effects on mortality of the insects in different post-irradiation periods; at 3rd day with doses of 1-3 kGy and at around 30th day 0.5-1 kGy. MBr fumigation caused the decrease in lightness (Hunter L value), total phenolics and reducing sugars and the increase in yellowness (Hunter b value) and browning intensity for the subjected samples, as compared with the nontreated control and irradiated ones at 0.5-2 kGy. Furthermore, MBr fumigation resulted in decay for the most part of samples during storage at 5-10 $^{\circ}C$ for 6 months in a PVC box packaging with nets. As a result, optimum levels of irradiation is expected to be roe of the alternatives to chemical fumigants.

• Imaging Science in Dentistry
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• v.44 no.1
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• pp.43-52
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• 2014

Purpose: This study was designed to evaluate whether magnetic resonance imaging (MRI) is appropriate for detecting early changes in the mandibular bone marrow and pulp tissue of rats after high-dose irradiation. Materials and Methods: The right mandibles of Sprague-Dawley rats were irradiated with 10 Gy (Group 1, n=5) and 20 Gy (Group 2, n=5). Five non-irradiated animals were used as controls. The MR images of rat mandibles were obtained before irradiation and once a week until week 4 after irradiation. From the MR images, the signal intensity (SI) of the mandibular bone marrow and pulp tissue of the incisor was interpreted. The MR images were compared with the histopathologic findings. Results: The SI of the mandibular bone marrow had decreased on T2-weighted MR images. There was little difference between Groups 1 and 2. The SI of the irradiated groups appeared to be lower than that of the control group. The histopathologic findings showed that the trabecular bone in the irradiated group had increased. The SI of the irradiated pulp tissue had decreased on T2-weighted MR images. However, the SI of the MR images in Group 2 was high in the atrophic pulp of the incisor apex at week 2 after irradiation. Conclusion: These patterns seen on MRI in rat bone marrow and pulp tissue were consistent with histopathologic findings. They may be useful to assess radiogenic sclerotic changes in rat mandibular bone marrow.

• Journal of Microbiology and Biotechnology
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• v.32 no.6
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• pp.808-815
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• 2022

In this study, gamma-irradiated mackerel (Scomber japonicus) meat was stored in a refrigerator for 20 days to examine the physicochemical changes related to fishy smell. The effect of gamma irradiation on the inhibition of the activity of crude urease extracted from Vibrio parahaemolyticus was also evaluated. Increased levels of trimethylamine (TMA) and volatile basic nitrogen (VBN) content, which are the main components causing fishy smell, were significantly reduced by day 20 of storage after gamma irradiation, indicating that freshness was maintained during storage. The ammonia nitrogen contents of 3, 7, 10, and 20 kGy gamma-irradiated groups were significantly decreased by 6.5, 15.2, 17.4, and 23.9%, respectively, compared to non-irradiated groups on day 20 of storage. In addition, urease activity decreased in a gamma irradiation intensity-dependent manner. Volatile organic compounds (VOCs) were measured during the storage of gamma-irradiated mackerel meat. The contents of ethanol, 2-butanone, 3-methylbutanal, and trans-2-pentenal, which are known to cause off-flavors due to spoilage of fish, were significantly reduced by day 20 of storage. Therefore, gamma irradiation can be considered useful for inhibiting urease activity and reducing fishy smell during fish storage.

• Journal of Food Hygiene and Safety
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• v.15 no.3
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• pp.248-251
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• 2000

Electron spin resonance (ESR) spectroscopy was used to detect irradiated chicken eggs, to investigate the effect of irradiation dose on the ESR signal intensity and to identify the stability of radicals under 77 days of storage. Raw chicken eggs were irradiated with doses of 0, 0.5, 1, 2, 3 and 5 kGy at room temperature using a Co-60 irradiator. The samples were prepared by separating, drying and powdering shells from the raw eggs. The irradiated chicken egg shells presented an asymmetric absorption in shape at g$_1$=2.0023$\pm$0.00004 and g$_2$=1.9979$\pm$0.00005, different from the non-irradiated ones. The strength of the ESR signal increased linearly with the applied doses (to S kGy). The intensity of the ESR signals after irradiation were stable even after 77-day of storage at 5$^{\circ}C$ and/or room temperature.

• Korean Journal of Food Science and Technology
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• v.45 no.2
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• pp.248-251
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• 2013

The purpose of this study was to investigate the inactivation effect of intense pulsed light (IPL) on Micrococcus roseus, an irradiation-resistant bacterium isolated from laver, and the commercial feasibility of this sterilization method on dried laver. The inactivation of M. roseus in cultivated plates increased with increasing light intensity and treatment time. Approximately 6.6 log CFU/mL reduction of the cell viability was achieved with IPL treatment for 3 min at 1,000 V of light intensity, tailing was not shown. In addition, the inactivation rate of M. roseus increased with increasing pulse number at same light intensity and treatment time. The killing efficiency for M. roseus increased with by decreasing the distance between the light source and the sample surface.