• Korean Journal of Food Science and Technology
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• v.37 no.2
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• pp.308-311
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• 2005

Electron beam irradiation was applied to examine microbial safety and qualities of black pepper powder and commercial Sunsik. Whole black pepper powder and commercial Sunsik were irradiated at 2, 4, 8, 12, and 16 kGy. Microorganism contamination in black pepper powder and commercial Sunsik were significantly decreased by irradiation. Decimal reduction doses ($D_{10}\;value$) of total bacteria count in black pepper powder and commercial Sunsik were 5.32 and 1.56 kGy, respectively. $D_{10}\;value$ of yeast and mold were 2.54 and 2.14 kGy for black pepper powder and commercial Sunsik, respectively. Electron beam irradiation caused negligible changes in Hunter color L, a, and b values. Sensory evaluations of black pepper powder and commercial Sunsik showed no significant changes among samples. These results indicate electron beam irradiation improves microbial safety and qualities of black pepper powder and commercial Sunsik.

• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.205-214
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• 2014

Purpose: Phytosanitary irradiation treatment can effectively control regulated pests while maintaining produce quality. The objective of this study was to establish the best irradiation treatment for mangosteen, a popular tropical fruit, using a Monte Carlo simulation. Methods: Magnetic resonance image (MRI) data were used to generate a 3-D geometry to simulate dose distributions in a mangosteen using a radiation transport code (MCNP5). Microsoft Excel with visual basic application (VBA) was used to divide the image data into seed, flesh, and rind. Radiation energies used for the simulation were 10 MeV (high-energy) and 1.35 MeV (low-energy) for the electron beam, 5 MeV for X-rays, and 1.25 MeV for gamma rays from Co-60. Results: At 5 MeV X-rays and 1.25 MeV gamma rays, all areas (seeds, flesh, and rind) were irradiated ranging from 0.3 ~ 0.7 kGy. The average doses decreased as the number of fruit increased. For a 10 MeV electron beam, the dose distribution was biased: the dose for the rind where the electrons entered was $0.45{\pm}0.03$ kGy and the other side was $0.24 {\pm}0.10$ kGy. Use of an electron kinetic energy absorber improved the dose distribution in mangosteens. For the 1.35 MeV electron beam, the dose was shown only in the rind on the irradiated side; no significant dose was found in the flesh or seeds. One rotation of the fruit while in front of the beam improved the dose distribution around the entire rind. Conclusion: These results are invaluable for determining the ideal irradiation conditions for phytosanitary irradiation treatment of tropical fruit.

• Food Science of Animal Resources
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• v.33 no.3
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• pp.335-340
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• 2013

This study screened for radio-resistant strains lactic acid bacteria (LAB) by evaluating their capability to survive exposure to ionizing radiation. Ten strains of LAB - Lactobacillus bulgaricus, Lactobacillus paracasei, Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus delbruekii, Lactococcus lactis, Streptococcus thermophilus, Bifidobacterium breve, and Pediocuccos pentosaceus - were selected and subcultuted twice. The LAB was then further cultured for 3 d at $37^{\circ}C$ to reach 7-10 Log colony-forming units (CFU)/mL prior to irradiation and immediately exposed to gamma rays or electron beams with absorbed doses of 0, 1, 2, 3, 4, 5, 6, 8, and 10 kGy. Gamma irradiation gradually decreased the number of the tested viable LAB, and the effect was irradiation dose dependent. A similar effect was found in electron beam-irradiated LAB. Radiation sensitivity of LAB was calculated as $D_{10}$ values, which ranged from 0.26 kGy to 0.9 kGy and 0.5 kGy to 1.44 kGy with exposure to gamma and electron beam irradiation, respectively, in all tested LAB. L. acidophilus was the most resistant to gamma and electron beam irradiation, with $D_{10}$ values of 0.9 kGy and 1.44 kGy, respectively. These results suggest that L. acidophilus might be suitable for the preparation of probiotics as direct-fed microbes for astronauts in extreme space environments.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.271-276
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• 2000

Electron beam (EB) irradiation was compared with gamma ray (GR) in terms of their effects on physicochemical qualities of microbial-decontaminated red pepper powder. The pH and soluble solid of the samples were relatively constant when exposed to EB and GR up to 15 kGy, which also did not induce significant chances in total and reducing sugars. The water soluble pigment and capsanthin content of red pepper powder showed a decreasing tendency as the irradiation dose increased. However, the pungent components, capsaicin and dihydrocapsaicin were shown resistant to irradiation doses applied. Based upon the results, EB was similar to GR in its effect on the physicochemical attributes of the samples, and the irradiation doses required for microbial control were not detrimental to the quality attributes of red pepper powder.

• Carbon letters
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• v.16 no.2
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• pp.121-126
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• 2015

Carbon fibers are prepared by stabilizing pitch fibers accompanying electron beam (E-beam) irradiation. The carbon fibers pretreated by E-beam irradiation achieve a higher stabilization index than the carbon fibers that are only heat-stabilized. In addition, the carbon fibers subjected to E-beam irradiation in the stabilization step exhibit a comparable tensile strength to that of general purpose carbon fibers. The carbon fibers pretreated with an absorbed dose of 3000 kGy have a tensile strength of 0.54 GPa for a similar fiber diameter. Elemental, Fourier-transform infrared spectroscopy, and thermogravimetric analyses indicate that E-beam irradiation is an efficient oxidation and dehydrogenation treatment for pitch fibers by showing that the intensity of the aliphatic C-H stretching and aromatic $CH_2$ bending (out-of-plane) bands significantly decrease and carbonyl and carboxylic groups form.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.4
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• pp.596-602
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• 2013

To investigate the synergistic effect(s) of electron-beam (EB) irradiation and leek (Allium tuberosum Rottler) extract on the quality of pork jerky during ambient storage, we irradiated prepared pork jerky samples (control and samples with 0.5% and 1.0% leek extract) with EB technology at doses of 0, 1, 2, and 4 kGy, stored them for 2 months at $25^{\circ}C$, and analyzed them. Water activity was 0.73 to 0.77 in non-irradiated samples, and no significant difference in the water activity was observed between the samples treated with leek and the control. The total aerobic bacterial count was significantly decreased with an increase in the irradiation dose and leek extract addition when compared to that of the control ($4.54{\pm}0.05$ log CFU/g). Further, the Hunter color values ($L^*$, $a^*$, and $b^*$) were found to be significantly decreased following leek extract addition and EB irradiation. However, the color values, especially the $a^*$ value of the irradiated samples significantly increased during storage. Notably, increasing the EB irradiation dose enhanced the peroxide value. Sensory evaluation revealed that irradiation decreased flavor and overall acceptability. Our findings suggest the use of EB irradiation in combination with leek extract to improve the microbiological safety of pork jerky. However, in order to meet market requirements, novel methods to enhance the sensory quality of pork jerky are warranted.

• Korean Journal of Food Science and Technology
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• v.30 no.6
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• pp.1362-1366
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• 1998

The sterilizing effect of electron beam was compared with that of gamma irradiation for commercial ginseng powders. White and red ginseng powders were contaminated by about $10^5\;CFU/g$ of total bacteria and by $10^3\;CFU$ of coliforms only in white ginseng powder. Data of microbial population for the sterilizing effect of electron beam irradiation showed that no microorganisms were detected in the samples irradiated up to 7.5 kGy for total aerobic bacteria and 2.5 kGy for molds and coliforms. Such doses were effective for controlling the microbial growth in the samples during 4 months of storage at room temperature. Decimal reduction doses $(D_{10}$ value) on the initial bacterial populations were $2.85{\sim}3.75\;kGy$ in electron beam and $2.33{\sim}2.44\;kGy$ in gamma irradiation, which were influenced by the initial microbial loads and the energy applied. Compared with gamma irradiation, electron beam showed a similar result in its sterilizing effect on ginseng powders, suggesting its potential utilization in due time.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.1
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• pp.71-87
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• 1995

The purpose of this study was to investigate the early irradiation changes on the ultrastructure of the capillary endothelial cell in the rat submandibular glands. For the study, 110 Sprague-Dawley strain male rats were singly irradiated to their neck regions with the doses of 2Gy, 5Gy, and 10Gy by 6MV X -irradiation, and sacrificed on the 3 hours, 6 hours, 12 hours, 1 day, 3 days, 7 days, and 14 days after irradiation. The authors observed the histologic and ultrastructural changes of the capillary endothelial cell using the light and electron microscopes. The results were as follows: I. In the light microscopic examination, the capillary dilation was observed on the 6 hours group and the capillary density was slightly increased on the 12 hours group after 2Gy and 5Gy irradiation. And luminal size and capillary density were decreased on the 3 days and the 7 days groups after irradiation, after then, they were recovered. But capillary density was still decreased on the 14 days group after 10Gy irradiation. 2. In the transmission electron microscopic examination, the mild proliferation of cytoplasmic process of the endothelial cell and reduction in luminal size were observed on the 3 hours group after irradiation. After then, endothelial swelling, marked proliferation of cytoplasmic process, thickened basal lamina, and numerous pinocytotic vesicles were observed after the 1 day group after irradiation. Thickened basal lamina and numerous pinocytotic vesicles were still observed until the 7 days group after irradiation. These changes were recovered to normal on the 14 days group after 2Gy and 5Gy irradiation, but not after 10Gy irradiation. 3. In the scanning electron microscopic examination, the dilation of conduits and constriction, and meandering were observed on the 1 day group after 10Gy irradiation. These changes were observed with increased coarseness of the surface of the vascular resin casting on the 3 days group after irradiation. 4. From the above results, endothelial swelling, proliferation of cytoplasmic process, and thickening of the basal lamina appeared before the 6 hours group after irradiation. And these changes may also induce the increase of the capillary number and luminal size, after then, capillary permeability was increased via the increase of the number of pinocytotic vesicles. The changes were observed earlier and more apparent with the increase of the irradiation doses under the dose of 10Gy irradiation.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.201-210
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• 2014

The influence of electron irradiation and hydrogen adsorption on the electronic structure of the $SrTiO_3$ (001) surface was investigated by ultraviolet photoemission spectroscopy (UPS). Upon electron irradiation of the surface, UPS revealed an electronic state within the band gap (in-gap state: IGS) with the surface kept at $1{\times}1$. This is considered to originate from oxygen vacancies at the topmost surface formed by electron-stimulated desorption of oxygen. Electron irradiation also caused a downward shift of the valence band maximum indicating downward band-bending and formation of a conductive layer on the surface. With oxygen dosage on the electron-irradiated surface, on the other hand, the IGS intensity was decreased along with upward band-bending, which points to disappearance of the conductive layer. The results indicate that electron irradiation and oxygen dosage allow us to control the surface electronic structure between semiconducting (nearly-vacancy free: NVF) and metallic (oxygen de cient: OD) regimes by changing the density of the oxygen vacancy. When the NVF surface was exposed to atomic hydrogen, in-gap states were induced along with downward band bending. The hydrogen saturation coverage was evaluated to be $3.1{\pm}0.8{\times}10^{14}cm^{-2}$ with nuclear reaction analysis. From the IGS intensity and H coverage, we argue that H is positively charged as $H^{{\sim}0:3+}$ on the NVF surface. On the OD surface, on the other hand, the IGS intensity due to oxygen vacancies was found to decrease to half the initial value with molecular hydrogen dosage. H is expected to be negatively charged as $H^-$ on the OD surface by occupying the oxygen vacancy site.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.1
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• pp.97-104
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• 2001

Decomposition of trichloroethlyene(TCE) in electron beam irradiation was examined on order to obtain information on the treatment of VOC in air. Air containing vaporized TCE has been studied in a flow reactor with different reaction environments, at various initial TCE concentration and in the presence and absence of water vapor. Maximum decomposition was observed in oxygen reaction environment and the degree of decomposition was about 99% at 20kGy for 2,000ppm initial TCE. The concentration of TCE exponentially decreased with dose in air and pure oxygen. The effect of water vapor on TCE decomposition efficiency was examined. The decomposition rate of TCE in the presence of water vapor (5,600 ppm) was approximately 10% higher than that in the absence of water vapor. Dichloroacetic acid, dichloroacethyl chloride and dichloroethyl ester acid were identified as primary products of this reaction adn were decomposed and oxidized to yield CO and $CO_2$. Perchloroethylene, hexachloroethane, chloroform and carbon tetrachloride were also observed as highly chlorinat-ed by products.