• Korean journal of food and cookery science
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• v.30 no.5
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• pp.603-612
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• 2014

According to the microbiological standard, Staphylococcus aureus, Clostridium perfringens and Listeria monocytogenes should not be detected in milk and egg products in Korea. Refrigerated food such as milk must be kept under $10^{\circ}C$ at retail markets. However, temperature abuse of refrigerated foods at such markets is often observed. We compared the growth and survival kinetics of S. aureus and C. perfringens at 10 and $15^{\circ}C$, and the growth kinetics of L. monocytogenes at 4 and $10^{\circ}C$ in whole and skim milk and ready-to-eat (RTE) quail eggs to evaluate their growth possibilities at retail markets. Regardless of storage temperature, the level of S. aureus reached the maximum level ($10^8-10^9CFU/ml$) in whole milk, non-fat milk and RTE quail eggs within the expiration date. Even low contamination levels of S. aureus (10 CFU/mL) grew rapidly in milk and quail eggs to reach the maximum level within the shelf life. Survival of C. perfringens in whole milk was greater than that in non-fat milk, indicating that the fat content in milk influences the survival of C. perfringens. For L. monocytogenes, the population in milk increased by 0.5-1 log CFU/mL at $4^{\circ}C$, while the populations reached the maximum level at $10^{\circ}C$ within the expiration date, regardless of initial contamination levels. In quail eggs, L. monocytogenes grew to the maximum level within the expiration date (60 days) at both temperatures. S. aureus and L. monocytogenes must be controlled to be negative, and proper temperature management should be emphasized at retail markets to protect the consumer. Since C. perfringens did not grow in milk and RTE quail eggs, there is no risk due to the growth of C. perfringens in these products at retail markets.

• Proceedings of the KSCN Conference
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• 2006.05a
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• pp.82-82
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• 2006

• Food Science and Preservation
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• v.14 no.5
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• pp.481-486
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• 2007

This study was conducted to evaluate the combined effect of gamma irradiation and silk peptide on the radiosensitivity of bacteria and the storage stability of ready-to-eat hamburger patty. The $D_{10}$ values obtained for Escherichia coli, Listeria ivanovii, Salmonella typhimurium and Clostridium sporogenes by gamma irradiation were 0.25, 0.50, 0.55 and 1.35 kGy, respectively. The inactivation rate of S. typhimurium ($D_{10}=0.53kGy$) inoculated into hamburger patty with 5%(w/w) silk peptide was reduced 6% compared with the control $D_{10}=0.558kGy$). In acceleration storage at $30^{\circ}C$, microorganisms were not observed in samples irradiated with 7 kGy or 10 kGy during storage. However the irradiation at 5 kGy was insufficient to sterilize the contaminated microorganisms in hamburger patty regardless of the addition of silk peptide (5%). These results indicate that the combined treatment of gamma-irradiation and silk peptide admixture could be helpful to ensure storage stability of ready-to-eat hamburger patty, by controlling the preliminary microbial load.

• Korean Journal of Food Science and Technology
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• v.52 no.6
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• pp.661-669
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• 2020

Samgak-Kimbap is a popular ready-to-eat (RTE) food at convenience stores, in Korea. Although Samgak-Kimbap is distributed through the cold chain supply system, inappropriate temperature storage conditions prior to consumption are a cause of concern. The objective of this study was to evaluate the risk of Staphylococcus aureus growth in Samgak-Kimbap in the retail market. The prevalence and contamination levels of S. aureus in Samgak-Kimbap (n=170) were monitored, and the predictive growth model of a five-strain cocktail of enterotoxin-producing S. aureus (SEA, SEB, SEC, SED, and SEE) was developed in Samgak-Kimbap as a function of temperature (4, 10, 11, 20, 25, and 37℃). We could not observe the growth of S. aureus and enterotoxin-producing S. aureus in Samgak-Kimbap at temperatures below 10℃. The probability of illness with S. aureus per serving of Samgak-Kimbap was 1.44×10-10 per day. The most influential factor in increasing the risk of foodborne illnesses was the contamination level of S. aureus in Samgak-Kimbap.

• Journal of Life Science
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• v.14 no.4
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• pp.664-669
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• 2004

The contamination of Bacillus cereus was investigated in 240 RTE (ready-to-eat) food samples including 118 seafoods, 82 Korean packaged meals and 40 other RTE foods. Many B. cereus presumptive strains were isolated from the enrichment culture in Tryptic Soy Broth (TSB) added polymyxin, followed by selective culture in Mannitol Egg Yolk Polymyxin (MYP) agar and Gram staining. A total of 36 strains (16 in seafoods, 17 in Korean pack-aged meals and 3 in other RTE foods) were identified as B. cereus by the analysis of 61 biochemical tests of the API 50CHB/20E system test and supplementary tests of $\beta$-hemolysis, rhizoid growth, motility and oxidase activity. The 28 strains out of 36 B. cereus isolates produced diarrhoeal enter-otoxin in Brain Heart Infusion (BHI) broth. All isolates were resistant to ampicillin and penicillin antibiotics, and most of them were susceptible to gentamicin, vancomycin, bacitracin, chloram-phenicol, kanamycin and streptomycin. The growth of B. cereus was affected by environmental temperature and incubation time. Culture with temperature under 1$0^{\circ}C$ effectively restricted the growth of B. cereus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.687-693
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• 2004

The objective of this study was to evaluate the combined treatment effect of gamma irradiation and rosemary extract powder on ready-to-eat hamburger steaks. After irradiation at 5, 10 and 20 k㏉, hamburger steaks manufactured with rosemary extract powder (200 and 500 ppm) were stored at 5$^{\circ}C$ for 4 months and at 3$0^{\circ}C$ for 3 weeks. Total aerobic bacteria count of the ready-to-eat hamburger steak was approximately 5 log CFU/g level. All doses of gamma irradiation were effective in reducing the population of total aerobic bacteria and coliform bacteria in hamburger steaks. In hamburger steaks irradiated at 20 k㏉, tile microbial growth was not observed during storage. The shelf-life of hamburger steaks were determined by microbiological counts of 10$^{6}$ ∼10$^{7}$ CFU/g and those of the steaks irradiated at 0, 5 and 10 k㏉ were ranged among 14, 28∼42 and 98∼112 days, respectively. The shelf-life of both irradiated hamburger steaks added with 500 ppm rosemary extract powder at 5 and 10 k㏉ was extended more 14 days than non-added sample. Results suggested that both gamma irradiation and rosemary extract powder may improve the shelf-stability of ready-to-eat ham-burger steak. However, when the storage temperature was abused (3$0^{\circ}C$), the rosemary extract powder had not sufficient effect on the shelf- stability of hamburger steaks.

• Proceedings of the Korean Society of Toxicology Conference
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• 2001.10a
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• pp.100-100
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• 2001

To develop an antimutagenic functional diet, the foods that have shown anticancer activity were mixed to make ready-to-eat powdered diets. The diets were prepared with various kinds of powdered cooked cereals, cooked legumes, oil seeds and sea tangles, and freeze-dried vegetables. The antimutagenic effects of methanol extracts from three mixed diets were investigated in the Ames test, SOS chromotest, and in vivo supravital staining micronucleus assay in the mice.(omitted)

• Food Science of Animal Resources
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• v.31 no.1
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• pp.40-46
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• 2011

The growth profile of Bacillus cereus in ready-to-eat (RTE) food products of animal origin was examined under different temperature and incubation conditions. In sandwiches and Kimbab, B. cereus did not grow or exhibited only minimal growth at 4 and $10^{\circ}C$, but it grew rapidly at ambient temperature. In sandwiches, B. cereus did not grow efficiently at $25^{\circ}C$, however, in ham, the main ingredient of sandwiches, B. cereus growth was observed at the same temperature, with bacterial levels reaching 7.94 Log CFU/g after incubation for 24 h at $25^{\circ}C$. Toxigenicity of B. cereus was observed only at temperatures above $25^{\circ}C$. In Kimbab, B. cereus produced toxin after 9 h at $30^{\circ}C$ and after 12 h at $25^{\circ}C$. Ingredients of sandwiches and Kimbab were collected from 3 different Korean food-processing companies to investigate the source of contamination by B. cereus. Among the 13 tested food items, 6 items including ham were found to be contaminated with B. cereus. Of these ingredients, B. cereus isolates from 3 items produced enterotoxins. None of these isolates harbored the emetic toxin-producing gene. The findings of the present study can be used for risk assessments of food products, including ham and cheese, contaminated with B. cereus.

• Food Science of Animal Resources
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• v.30 no.5
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• pp.780-786
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• 2010

This study compared the effects of autoclaving (AC; $121^{\circ}C$ for 15 min), gamma (GR), and electron beam irradiation (EB; 0-20 kGy) on the microbial, physicochemical, and sensory properties of ready-to-eat bulgogi during storage at $35^{\circ}C$ for 90 d. No viable cells were observed (p<0.05) upon AC, GR or EB at more than 15 kGy. However, adverse effects such as tenderization and deterioration of sensory properties were induced in bulgogi upon AC and high dose irradiation. Especially, the hardness and sensory qualities (texture and taste) of the AC-treated samples were extremely deteriorated (p<0.05). These results indicate that use of GR and EB (15 kGy) can ensure the microbial safety of bulgogi without compromising the hardness and sensory properties (texture, taste and flavor).

• Food Science of Animal Resources
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• v.30 no.5
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• pp.730-738
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• 2010

We developed predictive growth models for Staphylococcus aureus and Bacillus cereus on various food matrices consisting primarily of ready-to-eat (RTE) foods. A cocktail of three S. aureus strains, producing enterotoxins A, C, and D, or a B. cereus strain, were inoculated on sliced bread, cooked rice, boiled Chinese noodles, boiled bean sprouts, tofu, baked fish, smoked chicken, and baked hamburger patties at an initial concentration of 3 log CFU/g and stored at 8, 10, 13, 17, 24, and $30^{\circ}C$. Growth kinetic parameters were determined by the Gompertz equation. The square-root and Davey models were used to determine specific growth rate and lag time values, respectively, as a function of temperature. Model performance was evaluated based on bias and accuracy factors. S. aureus and B. cereus growth were most delayed on sliced bread. Overall, S. aureus growth was significantly (p<0.05) more rapid on animal protein foods than carbohydrate-based foods and vegetable protein foods. The fastest growth of S. aureus was observed on smoked chicken. B. cereus growth was not observed at 8 and $10^{\circ}C$. B. cereus growth was significantly (p<0.05) more rapid on vegetable protein foods than on carbohydrate-based foods. The secondary models developed in this study showed suitable performance for predicting the growth of S. aureus and B. cereus on various food matrices consisting of RTE foods.