• Journal of Radiation Industry
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• v.17 no.3
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• pp.257-264
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• 2023

This study was conducted to evaluate the applicability of the Comet assay, which is widely used for the identification of irradiated meats, to detect irradiated beef cut, ground beef, and Tteokgalbi during freezing storage. Gamma-irradiation significantly increased the DNA damage in frozen beef cut and ground beef samples. Among those, DNA nuclei of samples irradiated with absorbed doses of 1kGy or more showed typical comet-shaped damage, convincing that the samples were irradiated. Meanwhile, DNA nuclei in non-irradiated beef cut and ground beef samples were also damaged according to storage time. In particular, since the damage of DNA nuclei in the non-irradiated samples frozen for three months was similar to that of samples irradiated with a dose of 0.5 kGy, it was considered difficult to detect whether these samples were irradiated by Comet assay analysis. Likewise, gamma-irradiation of Tteokgalbi increased DNA damage. However, significant damage to DNA nuclei was observed even in the non-irradiated samples. Therefore, the application of the analysis method to determine whether the Tteokgalbi sample was irradiated was not appropriate. In conclusion, these results suggest that Comet assay could be limitedly applied only to fresh meat with a short storage period and minimal processing.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.638-645
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• 1999

This study was done to investigate effects of ${\gamma}$ irradiated beef feeding on the formation of gluta thione S transferase placental form positive(GST P+) foci, lipid peroxidation, cytochrome P450 system and microsomal glucose 6 phosphate activity in diethylnitrosamine(DEN) initiated rat hepatocarci nogenesis. Weaning Sprague Dawley male rats were fed the diet containing ${\gamma}$ irradiatied ground beef at the dose of 0, 3, 5kGy as a 20% of protein source for 8 weeks. One week after feeding, rats were intraperitoneally injected twice with a dose of DEN(50mg/kg BW). As a promoter, 0.05% phenobarbital was fed in drinking water from one week after DEN treatment until the end of experiment. At the end of 8th week, rats were sacrificed and hepatic GST P+ foci, microsomal malondialdehyde(MDA) and conjugated diene contents were determined. In addition, cytochrome P450 content and the activities of NADPH cytochrome P450 reductase and glucose 6 phosphatase were also measured. There was no significant effect by gamma irradiation on microsomal MDA content, conjugated diene, cytochrome P450 content and activities of NADPH cytochrome P450 reductase and glucose 6 phosphatase. However with DEN treatment, microsomal MDA content and conjugated diene contents were significantly changed. Cytochrome P450 content was also significantly increased while microsomal glucose 6 phophatase activity was significantly decreased with DEN treatment. However activity of NADPH cytochrome P450 reductase was not affected. An interesting finding in this study was that the number and area of hepatic GST P+ foci of the rats fed gamma irradiated beef were significantly(p<0.05) lower than those of the control. Such a lowering effect on GST P+ foci formation was highest at the dose of 3kGy than others. Overall results suggest that the consumption of low dose of gamma irradiated beef does not affect the formation of lipid peroxide, cytochrome P450 system and membrane stability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.3
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• pp.646-653
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• 1999

This study was done to investigate the effect of ${\gamma}$ irradiated beef feeding on antioxidant vitamin levels and defense enzyme activities in diethylnitrosamine(DEN) initiated rats. Weaning Sprague Dawley male rats were fed the diet containing ${\gamma}$ irradiated ground beef at the dose 0, 3, 5 kGy as a 20% of protein source for 8 weeks. One week after feeding, rats were intraperitoneally injected twice with a dose of DEN(50mg/kg BW). As a promoter, 0.05% phenobarbital was fed in drinking water from one week after DEN treatment until the end of experiment. At the end of 8th week, serum level of vitamin C, serum and hepatic levels of retinol and tocopherol were determined. In addition, activities of cytosolic glutathione peroxidase, glutathione reductase, glutathione S transferase, catalase and hepatic superoxide dismutase(SOD) were measured. By ${\gamma}$ irradiation, there was no significant effect on serum and hepatic levels of vitamin C and tocopherol except a significant decreasing effect on hepatic retinol level. There was also no significant effect on the activities of enzymes involved in antioxidative defense system, However, DEN treatment led to a significant increase in activities of glutathione reductase and glutathione S transferase while the activity of glutathione peroxidase was decreased. The activities of hepatic SOD and catalase were not changed by DEN treatment. Overall results indicate that the consumption of low dose of ${\gamma}$ irradiated beef does not affect antioxidative defense system.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.1005-1010
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• 1999

To study the shortening of rigor mortis and changes in the morphological properties of gamma-irradiated pre-rigor bovine muscle (M). Sternomandibularis during post mortem, this experiment was performed with a test of shear force and the observation of the ultrastucture of raw muscle. The time elapsed until maximum shear force values was shortened by gamma irradiation, depending upon the dose. The release of rigor mortis started earlier than control (non-irradiated muscle). A shortening of the length of the Z-line and the maintenance of the sarcomere length by gamma irradiation was observed. The breakdown of the perimysium of muscle bundles was observed more in irradiated samples than in the control. In conclusion, it is considered that gamma irradiation on pre-rigor beef shortens aging-period, improves tenderness and enhances the beef quality.

• Preventive Nutrition and Food Science
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• v.7 no.1
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• pp.57-61
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• 2002

Electron spin resonance (ESR) spectroscopy was used to investigate the effect of irradiation dose and storage time on the free radical concentrations in gamma-irradiated dried seasoning powder. Seasoning powders of dried squid flavor, shrimp flavors, kimchi flavor, spicy beef soup flavor and soy sauce flavor were irradiated with doses of 0, 1, 3, 5, 7 and 9 kGy at room temperature using a Co-60 irradiator. Characteristic signals of free radicals were observed in all the irradiated samples of this experimental while these signals were not detected in non-irradiated samples. Since the free radical concentrations linearly increased with the applied doses (1~9 kGy), highly positive correlation coefficients ($R^2$ = 0.9285~0.9965) were obtained between irradiation doses and free radical concentrations during all the storage times. Free radical concentrations of the irradiated flavored seasoning powder did not change even at 16 weeks of storage at room temperature, while those of dried squid, shrimp and spicy beef soup flavors decreased until 2 weeks of storage after irradiation with 5 kGy or over, and these of soy cause flavors slowly decreased until 8 weeks of storage after irradiation with 3 kGy or over. Although the free radical concentrations decreased with storage times, the characteristic signals of the irradiated seasoning powders of dried squid, shrimp, spicy beef and soy sauce flavors were observed even after 16 weeks of storage at room temperature.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1184-1188
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• 1998

Effects of gamma irradiation on pigments of beef was investigated by determination of the Hunter's color values and pigments such as myoglobin, metmyoglobin and oxymyoglobin after gamma irradiation up to 5 kGy in air or vacuum package for 7 days. 'L' and 'b' values increased but 'a' value decreased with the elapse of the storage period. But, 'L', 'a' and 'b' values of irradiated beef were lower than non-irradiated beef. Myoglobin decreased but oxymyoglobin and metmyoglobin increased with the elapse of the storage period. Myoglobin decreased but oxymyoglobin and metmyoglobin increased with gamma irradiation up to 5 kGy. In regard to packaging methods, vacuum package did not affect pigment of the beef as did air package.

• Food Science of Animal Resources
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• v.18 no.3
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• pp.232-239
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• 1998

This experiment was conducted to investigate radurization effects of gamma ray and electron beam irradiation at 1.5 and 3.0 kGy on beef steaks during 8 days of storage at 5$^{\circ}C$. Total bacteria count, psychrotrophs, mesophiles and thermophiles were analyzed at 2 days intervals. Nonirradiated beef steak was used a scontrol Total bacteria counts, psychrotrophs, mesophiles and thermophiles of the control samples showed 3.03∼4.72 logCFU / g at 0 day and increased to 7.67∼10.90 logCFU / g during 8 days storage except thermophiles. Total bacteria counts, psychrotrophs and mesophiles of beef steaks at 8 days were significantly (p＜0.05) decreased to 3.61∼5.43 logCFU / g by gamma ray and to 3.83∼7.02 logCFU / g by electron beam irradiation at 1.5 and 3.0 kGy. Thermophiles of all irradiated samples at any dose were not detectable through 8 days storage. These results suggested that both gamma ray and electron beam irradiation were effective to extend lag phase of bacterial growth of refrigerated beef. Gamma ray irradiation was better than electron beam irradiation in terms of radurization effects of beef.

• Korean Journal of Food Science and Technology
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• v.32 no.2
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• pp.363-372
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• 2000

Gamma irradiation$(1{\sim}5\;kGy)$ was applied to Korean beef to improve the hygienics and quality preservation. The effective dose of irradiation was 3 kGy for the sterilization of the initially contaminated microorganisms. After 8 weeks of storage at $5^{\circ}C$, no growth of the microorganisms were observed in the samples irradiated above 5 kGy. The pH was slightly increased as storage period increased. However, no significant change in pH was observed by gamma irradiation. The acid value of beef during storage at $5^{\circ}C$ was increased rapidly with the elapse of the storage period in both nonirradiated and irradiated samples, but that of the 3 kGy irradiated samples increased more slowly than the nonirradiated. VBN value increased more rapidly in nonirradiated sample than the irradiated during storage. Especially VBN value of the nonirradiated sample was four fold higher than that of the 3 kGy irradiated sample after 8 weeks of storage at $5^{\circ}C$. No significant differences in the components of fatty acid were observed by gamma irradiation. The amount of released free amino acid was increased during storage and was not significantly affected by gamma irradiation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.858-864
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• 1999

This study was conducted in order to evaluate the effect of gamma irradiation on improvement of the quality and safety of meat products. Emulsion type bologna sausages were manufactured with 3 kGy gamma irradiated ground beef. Beef patties were also manufactured with the addition of antioxidants (200 ppm, BHA, ascorbyl palmitate, ${\alpha}-tocopherol,\;or\;{\beta}-carotene$) following gamma irradiation of 1.5 or 3 kGy. Bologna sausages could be successfully manufactured with 3 kGy gamma irradiated ground beef and lower salt content(NaCl of 1.0 or 1.2% and phosphate of 0.2 or 0.3%) without any deteriorative results when compared with the products manufactured with regular salt content(NaCl of 1.5~2.0% and phos phate of 0.4~0.6%). No colony formations of aerobic microorganisms were observed in the sausage with NaCl of 1.2% and phosphate of 0.2 or 0.3% up to 30 days storage at $10^{\circ}C$. No significant differences appeared in the TBA values among all the sausages during storage for 30 days. No colonies of aerobic microorganisms were observed in the 3 kGy irradiated patty. Lipid oxidation of the beef patties was inhibited by the addition of an antioxidant.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.6
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• pp.1025-1029
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• 2000

This study was conducted to investigate whether a DNA comet assay could be applied for identifying irradiated pork and beef. Pork and beef were irradiated with Co-60 gamma rays at 0.1, 0.3, 0.5, 0.7 and 1.0 kGy, and stored in a freezer Cells separated from the samples were embedded in agarose gel on a slide, dissolved in a lysis solution, and electrophoresed at 2 V/cm for 2.0 min by horizontal electrophoesis. The cells were then stained with a silver staining in order to visualize the DNA using a micro-scope. The DNA fragments of the irradiated cells stretched or migrated out of the cells and formed tails towards the anode, giving the appearance of comets, while unirradiated cells formed very short or no tails. The distance of DNA migration increased with irradiation dose. Since the statistical analysis showed a significant correlation between tail length and irradiation dose, a DNA comet assay could provide not only identification but also estimation of the irradiation dose for irradiated beef and pork.