• Preventive Nutrition and Food Science
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• v.17 no.2
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• pp.172-176
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• 2012

Doenjang is a traditional Korean fermented soybean product that provides a major source of protein. In this study, a total of 18 different home-made doenjang samples were examined for the presence of foodborne pathogens and the total aflatoxin levels. Using an enzyme-linked immunosorbent assay to assess microbial quality and potential public health risk, we showed that total coliform levels in the doenjang samples ranged from 0 to $4.43{\pm}2.32{\times}10^6\;CFU/g$, and the maximum limit of Bacillus cereus was $4.67{\pm}2.0{\times}10^5\;CFU/g$. However, other foodborne pathogens, such as Staphylococcus aureus, Escherichia coli O157:H7 and Salmonella spp., were not detected among the tested samples. One of the samples (S3) showed a maximum limit of $42.2{\pm}9.1\;{\mu}g/kg$ for aflatoxin levels, which was above the safety limit allowed by the Codex Alimentarius Commission (CAC) regulatory agency. Further research is necessary to determine whether and how doenjang safety can be improved via elimination/reduction of microbial contamination during fermentation and storage or using microbial starter cultures for its fermentation.

• Journal of Environmental Science International
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• v.20 no.5
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• pp.575-580
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• 2011

This study characterized water quality of groundwater and purified water used for drinking water in 30 schools in Gyeongsangbukdo Province. The results of the study showed that 43% of groundwater and 45% of purified water were not suitable for drinking. Among them, microbial contaminations were the most serious problem. In raw groundwater, the exceeding rates of total colony counts was the highest in August (53.6%). Purified water samples showed higher rate of exceeding drinking water standard for total colony counts while showing lower rate of exceeding drinking water standard for total coliforms and fecal coliforms in March and August. Overall, proper managements for microbial contaminations are required for both groundwater and purified water. Furthermore, special attention should toward students not to drink water when groundwater or purified water exceeds the drinking water quality standard.

• The Korean Journal of Food And Nutrition
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• v.23 no.2
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• pp.240-246
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• 2010

This study aimed to determine microbiological quality on vegetable salad used dressing added with Prunus mume extracts. For this study, Dressing were blended with Prunus mume extracts to different concentrations of 0, 10, and 20%. Microbiological effects of vegetable salad used dressing added with Prunus mume extracts were assessed during production process by measuring process time, temperature, pH and Aw and determining total plate counts and coliforms. Effects of vegetable salad used dressing added with Prunus mume extracts on total plate counts and coliforms were observed during holding at 3, $25{\pm}1^{\circ}C$ for 12 hours. Dressing added with Prunus mume extracts improved the microbiological quality and showed antibacterial properties when they are added to vegetable salad.

• Preventive Nutrition and Food Science
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• v.11 no.3
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• pp.257-260
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• 2006

The correlation between microbiological and sensory quality indexes was investigated for Korean seasoned side dishes stored under chilled conditions, by using both published data and experimental evaluation. Aerobic bacterial counts on the perishable Korean side dishes showed high inverse correlation with sensory quality and could also be regarded as a main cause of sensory quality deterioration. Therefore, monitoring or estimating the microbial growth on these products should be an effective means for estimating and extending their shelf life.

• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1392-1396
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• 1999

This work was to apply the microwave energy to HTST pasteurization of milk in order to prevent undesirable quality changes due to the fouling and overheating on the surface of heat exchanger. A continuous tubulartype microwave pasteurization system was designed using a domestic microwave oven(800w and 2,450MHz). Raw milk was HTST pasteurized$(at\;72^{circ}C\;for\;15\;sec)$ by three methods; by heating in a stainless steel tube immersed in a hot water bath(MP0), by heating in a microwave cavity to a desired temperature and then holding in a hot water bath(MP1) and by both heating and holding in a microwave cavity(MP2). The microbial quality based on the total plate count and Psychotrophic bacterial count was in the order MP0, MP2 and MP1 ; however, the quality difference was not significant(p<0.05) when the initial microbial numbers were involved in the statistical analysis. In addition, the three samples pasteurized by different methods showed the similar microbial quality based on the coliform count and phosphatase activity. The similar microbial quality of the three samples supports the potential use of microwave energy for the pasteurization of milk and other fluid food products.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.4
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• pp.585-594
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• 2018

Objective: This study was to determine the bacterial diversity and monitor the community dynamic changes during storage of vacuum-packaged sliced raw beef as affected by Lactobacillus sakei and Lactobacillus curvatus. Methods: L. sakei and L. curvatus were separately incubated in vacuumed-packaged raw beef as bio-protective cultures to inhibit the naturally contaminating microbial load. Dynamic changes of the microbial diversity of inoculated or non-inoculated (control) samples were monitored at $4^{\circ}C$ for 0 to 38 days, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Results: The DGGE profiles of DNA directly extracted from non-inoculated control samples highlighted the order of appearance of spoilage bacteria during storage, showing that Enterbacteriaceae and Pseudomonas fragi emerged early, then Brochothrix thermosphacta shared the dominant position, and finally, Pseudomonas putida showed up became predominant. Compared with control, the inoculation of either L. sakei or L. curvatus significantly lowered the complexity of microbial diversity and inhibited the growth of spoilage bacteria (p<0.05). Interestingly, we also found that the dominant position of L. curvatus was replaced by indigenous L. sakei after 13 d for L. curvatus-inoculated samples. Plate counts on selective agars further showed that inoculation with L. sakei or L. curvatus obviously reduced the viable counts of Enterbacteraceae, Pseudomonas spp. and B. thermosphacta during later storage (p<0.05), with L. sakei exerting greater inhibitory effect. Inoculation with both bio-protective cultures also significantly decreased the total volatile basic nitrogen values of stored samples (p<0.05). Conclusion: Taken together, the results proved the benefits of inoculation with lactic acid bacteria especially L. sakei as a potential way to inhibit growth of spoilage-related bacteria and improve the shelf life of vacuum-packaged raw beef.

• Journal of Biosystems Engineering
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• v.30 no.1 s.108
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• pp.17-24
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• 2005

An efficient microbial control system was introduced into a garlic peeling system using pressurized water in order to improve the quality and the shelf-life of peeled garlic. High microbial density of the spoiled peeled garlic and the water used for peeling and washing indicated that an efficient microbial control system is necessary far the peeling system. Though Pseudomonas spp. and Penicillium spp. were closely related to the spoilage of peeled garlic, the spoilage of peeled garlic was thought to be caused mainly by nonspecific increase in microbial density. The shelf-life of the garlic peeled by pressurized water was longer than that of the garlic peeled by pressurized air, and the degree of damage had great effect on the shelf-life of peeled garlic. Ozonated water was effective in decreasing the microbial contamination and in increasing the shelf-life of peeled garlic. Based on the findings of the study, following improvements were made to the garlic peeling system using pressurized water; 1) the water circulation system was modified in order to completely separate the water for washing from the water for garlic peeling, 2) filtration and cooling equipments were introduced into the circulation system of the water for peeling, and 3) an ozone generator which could continuously supply ozonated water (dissolved ozone concentration of 0.4 ppm) was attached to the circulation system of the water for washing.

• Environmental Engineering Research
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• v.14 no.2
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• pp.120-125
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• 2009

Water stress has become a major concern in agriculture. Korea suffers from limited agricultural water supply, and wastewater reuse has been recommended as an alternative solution.A study was performed to examine the effects of microorganism concentration in the ponded-water of a paddy rice field with reclaimed-water irrigation for evaluating the microbial risk to farmers and neighborhoodchildren.Most epidemiological studies were performed based on an upland field, and they may not directly applicable to paddy fields. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion. Their risk value increased significantly high level after irrigation and precipitation.It implies that agricultural activities such as plowing, and fertilizing, and precipitation need be practiced a few days after irrigation considering health risks. The results about field application of the microbial risk assessment using E. coli showed difference according to monitoring time and treatment plot. Result of the microbial risk assessment showed that risk values of ground-water and reclaimed secondary waste water irrigation were lower than directly use of wastewater treatment plants' effluent. This paper should be viewed as a first step in the application of quantitative microbial risk assessment of E. coli to wastewater reuse in a paddy rice farming.

• Animal Bioscience
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• v.36 no.10
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• pp.1596-1603
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• 2023

Objective: Sous-vide cooking offers several advantages for poultry meat, including enhanced tenderness, reduced cooking loss, and improved product yield. However, in duck meat, there are challenges associated with using the sous-vide method. The prolonged cooking time at low temperatures can lead to unstable microbial and oxidative stabilities. Thus, we aimed to assess how varying sous-vide cooking temperatures and durations affect the physicochemical and microbial characteristics of duck breast meat, with the goal of identifying an optimal cooking condition. Methods: Duck breast meat (Anas platyrhynchos) aged 42 days and with an average weight of 1,400±50 g, underwent cooking under various conditions (ranging from 50℃ to 80℃) for either 60 or 180 min. Then, physicochemical, microbial, and microstructural properties of the cooked duck breast meat were assessed. Results: Different cooking conditions affected the quality attributes of the meat. The cooking loss, lightness, yellowness, Hue angle, whiteness, and thiobarbituric acid reactive substance (TBARS) values of the duck breast meat increased with the increase in cooking temperature and time. In contrast, the redness and chroma values decreased with the increase in cooking temperature and time. Cooking of samples higher than 60℃ increased the volatile basic nitrogen contents and TBARS. Microbial analysis revealed the presence of Escherichia coli and Coliform only in the samples cooked at 50℃ and raw meat. Cooking at lower temperature and shorter time increased the tenderness of the meat. Microstructure analysis showed that the contraction of myofibrils and meat density increased upon increasing the cooking temperature and time. Conclusion: Our data indicate that the optimal sous-vide method for duck breast meat was cooking at 60℃ for 60 min. This temperature and time conditions showed good texture properties and microbial stability, and low level of TBARS of the duck breast meat.

• Journal of Life Science
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• v.27 no.9
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• pp.1086-1095
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• 2017

There is growing interest in groundwater resources to overcome the loss of surface water resources due to climate change. An understanding of the microbial community of aquifers is essential for monitoring and evaluating groundwater contamination, as well as groundwater management. Most microorganisms that inhabit aquifer ecosystems are attached to sediment particles rather than planktonic, as is the case in groundwater. Since sampling aquifer sediment is not easy, groundwater, which contains planktonic microorganisms, is generally sampled in microbial community research. Although many studies have investigated microbial communities in contaminated aquifers, there are only a few reports of microbial communities in uncontaminated or pristine aquifers, resulting in limited information on aquifer microbial diversity. Such information is needed for groundwater quality improvement. This paper describes the ecology and community structure of groundwater bacteria in uncontaminated aquifers. The diversity and structures of microbial communities in these aquifers were affected by the concentration or distribution of substrates (e.g., minerals, organic matter, etc), in addition to groundwater characteristics and human activities. Most of the microbial communities in these uncontaminated aquifers were dominated by Proteobacteria. Studies of microbial communities in uncontaminated aquifers are important to better understand the biogeochemical processes associated with groundwater quality improvement. In addition, information on the microbial communities of aquifers can be used as a basis to monitor changes in community structure due to contamination.