• Journal of the Korean Society of Food Science and Nutrition
• /
• v.32 no.1
• /
• pp.137-142
• /
• 2003

This study was carried out to examine the effects of gamma irradiation on the color removal, antioxidation, DPPH radical scavenger, and antimicrobial activity of Schizandra fructus extracts by different solvents. Schizandra fructus was extracted by hot water, ethanol, acetone and methanol, and the extracts were irradiated 10, 20 and 30 kGy with gamma rays. Hunter color L-value was increased by irradiation in a dose-dependent manner, resulting in brighter color for all solvents used. The a and b values were decreased by irradiation in a dose-dependent manner. Antioxidant activity of the ethanol extract of Schizandra fructus against soybean oil was the highest. The free radical scavenging activity was the strongest in hot water extract. All solvent extracts from Schizandra fructus had the strongest antimicrobial activities to B. subtilis, B. natto, B megaterium, S. aureus, Sal. typhymurium and E. coli. These results suggested that Schizandra fructus extracts have a strong potential as natural food preservatives and cosmetic raw materials. Furthermore, irradiation may not influence adversely on biological activites of the extracts when irradiated up to 30 kGy.

• Food Science and Biotechnology
• /
• v.14 no.2
• /
• pp.181-184
• /
• 2005

Effects of irradiation and fumigation on disinfestation and quality attributes of chestnuts during storage were studied. Fresh chestnuts were exposed to gamma irradiation (0-10 kGy) and methyl bromide (MeBr) under commercial conditions and stored at different temperatures for 6 months. Pest of quarantine importance for chestnuts, Curculio sikkimensis Heller showed 100% mortality by MeBr on 3rd day after fumigation and by irradiation at 0.5 kGy in about 3 weeks at $23{\pm}0.5^{\circ}C$. Respiration rates of samples one day after treatments increased in proportion to irradiation dose. Respiration pattern of MeBr group was equal to that of 10 kGy-group. Both MeBr and irradiation at 0.25 kGy or higher showed 100% inhibition of sprouting during storage at $5^{\circ}C$ for 6 months. Flesh firmness was significantly reduced by MeBr or irradiation over 5 kGy (p<0.05) 1 day after treatments. MeBr fumigation resulted in appreciable decrease in flesh weight, reducing sugar and ascorbic acid contents (p<0.05), as compared to irradiated samples. Irradiation at 0.5 kGy was effective as alternative to MeBr in controlling pests while maintaining overall quality of fresh chestnuts during storage.

• Food Science and Preservation
• /
• v.14 no.3
• /
• pp.239-246
• /
• 2007

The effects of gamma irradiation on the physiochemical and physical characteristics of apples were investigated during post-irradiation storage at $4^{\circ}C\;and\;25^{\circ}C$. The contents of total and reducing sugars were analyzed and the results indicated that apples receiving 1 kGy of gamma irradiation did not show significant differences in sugar contents compared to non-irradiated controls. Important physiological characteristics were evaluated by measurement of total phenolic content and total flavonoid content, reducing power, and radical scavenging ability, and the results indicated that gamma irradiation at a dose of 1 kGy did not affect physiological activities. Changes in physical parameters such as weight loss, strength, cohesiveness and hardness, during post-irradiation storage, were temperature-dependent, whether the apples were irradiated or not The color and sensory acceptance of the apples were not affected by irradiation during cold storage. However, minor deterioration in color quality and sensory acceptance of irradiated apples was noted under ambient temperature storage. We conclude that gamma irradiation(1 kGy) does not affect apple nutritional content stability, functional properties, or physical characteristics, especially upon cold storage after radiation treatment.

• Korean Journal of Food Science and Technology
• /
• v.19 no.5
• /
• pp.403-408
• /
• 1987

The effects of gamma irradiation on microbiological and chemical qualities of four kinds of poultry feeds were investigated. The viable counts of total bacteria in the samples were $10^5\;to\;10^6/g$. They were reduced by 2 to 3 log cycles after 3 to 5 kGy irradiation, and were completely eliminated with irradiation of 7 kGy. Coliforms and enteric pathogens were contaminated in high levels in all samples, ranging from $1.2{\times}10^4\;to\;1.7{\times}10^5/g\;and\;4.0{\times}10\;to\;2.6{\times}10^3/g$, respectively, They were sterilized by 3 to 5 kGy irradiation. Fungi, ranging from $10^{2}\;to\;10^4/g$, mainly osmophiles were identified as Aspergillus and Penicillium. They were eliminated to a undetectable level by 5 to 10 kGy irradiation. Six kinds of species, including Aspergillus flavus, were potential mycotoxin producers. Chemical components, such as proximate compositions, and mineral contents were not affected by the gamma irradiation. However, TBA values and amino acid content seemed to be affected by gamma irradiation.

• Nuclear Engineering and Technology
• /
• v.52 no.8
• /
• pp.1764-1770
• /
• 2020

The present work was mainly concerned with studying the operation of RC-phase shift oscillator based on MOSFET type 2N6660 under the influence of different temperature levels ranging from room temperature (25 ℃) up-to135 ℃ and gamma-irradiation up-to 3.5 kGy. In this concern, both the static (I-V) characteristic curves of MOSFET devices and the output signal of the proposed oscillator were recorded under ascending levels of both temperature and gamma-irradiation. From which, it is clearly shown that the drain current was decreased from 0.22 A, measured at 25 ℃, down to 0.163 A, at 135 ℃. On the other hand, its value was increased up-to 0.49 A, whenever the device was exposed to gamma-rays dose of 3.5 kGy. Considering RC-phase shift oscillator, the oscillation frequency and output pk-pk voltage were decreased whenever MOSFET device exposed to gamma radiation by ratio 54.9 and 91%, respectively. While, whenever MOSFET device exposed to temperature the previously mentioned parameters were shown to be decreased by ratio 2.07 and 46.2%.

• Preventive Nutrition and Food Science
• /
• v.8 no.2
• /
• pp.158-161
• /
• 2003

This study investigated the effects of a ${\gamma}$-irradiated pork (0-30 kGy) diet on lipid peroxidation, cytochrome P-450 content, microsomal glucose 6-phosphatase (G-6-Pase) activity and antioxidative defense systems in diethylnitrosamine (DEN)-induced rat hepatocarcinogenesis. The body weight of rats fed irradiated diets did not change significantly. Liver weight was significantly increased by the administration of DEN, but not by irradiated diets at any dose level. There were no significant effects of gamma irradiation on the content of microsomal malondialdehyde (MDA), cytochrome P-450, or on the activity of G-6-Pase. However, with DEN treatment, cytochrome P-450 content was significantly increased while microsomal G-6-Pase activity was significantly decreased. The ${\gamma}$-irradiated diet supplement did not affect serum retinol or $\alpha$-tocopherol concentrations. However, it did cause a significant decrease in hepatic retinol at 30 kGy. With DEN treatment, hepatic retinol content was even more significantly (p<0.05) decreased compared to the non-irradiated control. The enzyme activities related to antioxidative defense systems, including glutathione peroxidase (GSH-Px), glutathione reductase (GSH-Rx) and glutathione S-transferase (GST) were not affected by gamma irradiation. Those results suggest that an irradiated pork diet up to 30 kGy may not cause a health hazard in experimental animals.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.30 no.5
• /
• pp.777-781
• /
• 2001

The effects of gamma-irradiation on the nutritional components of some Korean soybean-based fermentation foods were studied. Doenjang (soybean paste), kochujang (red pepper paste) and chungkukjang were prepared, irradiated at 0, 5, 10 and 20 kGy, and their compositions of free amino acid, free fatty acid and organic acid were determined. Compositions of free amino acid and free fatty acid in gamma irradiated sample were stable compared to non-irradiated control. Content of citric acid and succinic acid increased, while that of malic acid decreased in the gamma irradiated chungkookjang, but there were no significant changes in organic acid composition in organic and kochujang.

• Korean Journal of Microbiology
• /
• v.6 no.2
• /
• pp.41-53
• /
• 1968

Studies on the carbohydrate metabolism of yeast as influenced by gamma-irradiation from cobalt-60 have been carried, then the mechanisms of radiation effect on respiration and fermentation were discussed under considerations of permeable changes of irradiated cell membrane. The cells of baker's yeast (Saccharomyces cerevisiae) which had been gamma-irradiated of 240 k.r. doses for an hour, then were put into aerobic oxidation and anaerobic fermentation without substrate. Total and fractionated carbohydrates of irradiated yeast cells were determined by calorimetric method with anthrone and orcinol reagents, the amounts of total carbohydrate, trehalose, RNA-ribose, PCA-soluble glycogen, alkali-soluble glycogen, acetic acid-soluble glycogen, mannan and glucan were determined according to the course of aerobic oxidation and anaerobic fermentation. It is found that the carbohydrates of irradiated cells leak out and amount of the losses teaches eleven times more than that of control, the volume of losses are seems to be replaced by water, it can be suggested the damage of gamma-irradiation occurs in the site of passive transport of cell membrane. The endogeneous aerobic respiration of irradiated cells are increased much more than control, the synthesis of reserve glycogen, glucan and RNA-ribose promoted much more than control. The anaerobic fermentation of irradiated cells are also increased than that of control, but the breakdown of carbohydrate is less than endogeneous respiration of irradiated cells. The synthetic rate is also less than that of aerobic oxidation. In irradiated yeast cells, trehalose is revealed to be primary substrate for endogeneous carbohydrate metabolism, so it is proved that the enzymic patterns are not changed but the activities of enzymes relating endogeneous respiration and autofermentation is activated. It is to be considerable to distiguish endogeneous respiration and autofermentation from exogeneous respiration and fermentation on irradiation, for membrane permeability changes and loses out carbohydrate by ionizing radiation.

• Molecules and Cells
• /
• v.27 no.2
• /
• pp.263-268
• /
• 2009

Gamma knife surgery (GKS) is used for the treatment of various human brain disorders. However, the biological effects of gamma ray irradiation on both the target area, and the surrounding tissues are not well studied. The effects of gamma ray exposure to both targeted and untargeted regions were therefore evaluated by monitoring gene expression changes in the unilateral irradiated (60 Gy) and contralateral un-irradiated striata in the rat. Striata of irradiated and control brains were dissected 16 hours post-irradiation for analysis using a whole genome 44K DNA oligo microarray approach. The results revealed 230 induced and 144 repressed genes in the irradiated striatum and 432 induced and 239 repressed genes in the unirradiated striatum. Out of these altered genes 39 of the induced and 16 of the reduced genes were common to both irradiated and un-irradiated tissue. Results of semiquantitative, confirmatory RT-PCR and western blot analyses suggested that ${\gamma}$-irradiation caused cellular damage, including oxidative stress, in the striata of both hemispheres of the brains of treated animals.

• Journal of radiological science and technology
• /
• v.3 no.1
• /
• pp.95-105
• /
• 1980

In this paper, the author studied the histological changes of the midgut cells of fall webworms(Hyphantria cunea Drury) through 1.75-7 krad of the whole body gamma irradiation according to their metamorphosis by comparing the contol group with the irradiated one through an optical microscope. Here the results were as follows: 1. The epithelium of midgut was composed of columnar, goblet and regenerative cells. 2. The effects of gamma irradiation were varied with the dosages and the stages during the metamorphosis. 3. The degree of histological change mode by irradiation was increased with the dosages. 4. Radiosensitivity was the highest in both last-stage larva and 8-day-old pupae.