• Journal of Microbiology
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• v.38 no.2
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• pp.99-104
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• 2000

Hydrogen peroxide has been used in cleaning the piping of an advanced high-purity water system that supplies ultra-high purity water (UHPW) for 16 megabyte DRAM semiconductor manufacturing. The level of hydrogen peroxide-resistant bacteria in UHPW water was monitored prior to and after disinfecting the piping with hydrogen peroxide. Most of the bacteria isolated after hydrogen peroxide disinfection were highly resistant to hydrogen peroxide. However, the percentage of resistant bacteria decreased with time. The hydrogen peroxide-resistant bacteria were identified as Micrococcus luteus, Bacillus cereus, Alcaligenes latus, Xanthomonas sp. and Flavobacterium indologenes. The susceptibility of the bacteria to hydrogen peroxide was tested as either planktonic cells or attached cells on glass. Attached bacteria as the biofilm on glass exhibited increased hydrogen peroxide resistnace, with the resistance increasing with respect to the age of the biofilm regrowth on piping after hydrogen peroxide treatment. In order to optimize the cleaning strategy for piping of the high-purity water system, the disinfecting effect of hydrogen preoxide and peracetic acid on the bacteria was evaluated. The combined use of hydrogen peroxide and peracetic acid was very effective in killing attached bacteria as well as planktonic bacteria.

• Journal of environmental and Sanitary engineering
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• v.4 no.2 s.7
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• pp.33-45
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• 1989

The survey was conducted on the actual conditions of species, the facilities, a establishment of regulation concerning laboratory animals and the related problems on users and suppliers of laboratory animals in Korea. The questionnaires were sent to 430 and received from 107$(24.9\%)$ places. The results obtained were as follows : 1. Experimental animals used at the 107 places were 21 species: mouse(90\;places,\;84.1\%)$, rat $(61,\;57.0\%)$, rabbit$(76,\;71.0\%)$, guineapig$(42,\; 39.3\%)$ etc. 2. The main organizations using laboratory animals were university $46(43.0\%)$, institute $32(29.9\%)$ and pharmaceutical company $27(25.2\%)$ etc. 3. Most the laboratory animal facilities in Korea have been conventional system without environmental controls, but a few places have been recently established barrier system. 4. To get a good experimental result, a regular genetic and microbiological monitoring of laboratory animals should be done. 5. It was required that a educational facilities and a quality test agency for laboratory animals should be established. 6. It was also required that a regulation for breeding and using of laboratory animals should 'be enacted.

• Journal of Food Hygiene and Safety
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• v.27 no.3
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• pp.301-305
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• 2012

This study was conducted to investigate the microbiological contamination levels in rice cakes and rice flour due to climate change in three areas classified to their temperature and precipitation. We investigated the contamination levels of total aerobic bacteria, coliforms, Escherichia coli, Bacillus cereus, Staphylococcus aureus, Clostridium perfringens of rice flour and 3 rice cakes such as Garaetteok, Sirutteok and Gyeongdan. Contamination levels of total aerobic bacteria in rice flour were 4.9 log CFU/g. In a total of 70 rice flour, yeasts & molds and coliforms were detected in 42 and 52 samples at the levels of 43 CFU/g and 1.29 log CFU/g, respectively. S. aureus were detected in only 1 rice flour (1.66 log CFU/g) out of 70. In an investigation of contamination levels in rice cakes, the population of total aerobic bacteria were highest in Gyeongdan (5.18 log CFU/g) and coliforms were highest in Gareattock (2.93 log CFU/g). There was no detection of E. coli and B. cereus except for only 1 Gareattock (1.20 log CFU/g). There were no differences of contamination levels among the three areas. If constant monitoring of rice cakes and rice flour is conducted on the basis of this study, it is expected to be able to analyze the change of contamination levels in rice cakes and rice flour due to climate change.

• Journal of Food Hygiene and Safety
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• v.36 no.5
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• pp.400-406
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• 2021

The purpose of this study was to evaluate the microbial contamination level of Korean traditional rice cakes (Garaetteok, Injeolmi, Gyeongdan), as well as manufacturing environment of small-sized businesses in Korea. The contamination levels of total aerobic bacteria, coliforms, and Bacillus cereus in raw materials were 3.76-4.48, 2.21-4.14, and 1.02-1.15 log CFU/g respectively. On the other hand, Escherichia coli was not found. It has been found that the contamination level of total aerobic bacteria, coliforms, and B. cereus in the raw material decreased after the washing process, but it increased again during the soaking and grinding process. However, after the steaming stage, the contamination level increased again during the molding and cooling process, suggesting the need to take cautions in managing cooling water and molded rice cakes in the process. These results suggest that the safe management of cooling water and taking cautions in the drying process after steaming of rice cakes are necessary for controlling cross-contamination. No E. coli was detected during the manufacturing process involving all tested rice cakes. The microbial contamination level of manufacturing environment such as rice grinder and rice cake forming machine was high. Therefore, in terms of food safety strategy, it is necessary to consider introducing systematic cleansing and disinfection procedure to processing equipment and environment for the sake of reducing microbiological risks.

• Journal of Animal Science and Technology
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• v.62 no.5
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• pp.682-691
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• 2020

Careful cleaning and disinfection of pigpens is essential to prevent disease spread and avoid the resultant economic losses. Hygiene in pigpens is generally evaluated by visual monitoring supplemented with bacteriological monitoring, which includes counting the total aerobic bacteria (TAB) and/or fecal indicator bacteria (FIB). However, these methods present drawbacks such as time and labor requirements. As adenosine triphosphate (ATP) is ubiquitous in all living organisms including microorganisms, this study aimed to directly compare the results of microbial assessment and ATP quantification, and to suggest possible detailed application methods of the ATP test for hygiene evaluation in pigpens of a farrowing unit. Before and after standard cleaning procedures, samples were collected from the floor corner, floor center, and feeding trough of four pigpens at different time points. No FIB were detected and both the TAB and ATP levels were significantly decreased in the floor center area after cleaning. FIB were continuously detected after cleaning and disinfection of the floor corners, and there was no significant ATP level reduction. The feeding trough did not show any significant difference in these values before and after cleaning, indicating insufficient cleaning of this area. The levels of TAB and ATP after cleaning were significantly correlated and the average ATP value was significantly lower in the absence of FIB than in their presence. In the absence of standard references, a more thorough hygiene management could be achieved evenly by supplementing cleaning or disinfection based on the lowest ATP results obtained at the cleanest test site, which in the present study was the floor center. Overall, these results indicate that the on-farm ATP test can be used to determine the cleanliness status, in addition to visual inspection, as an alternative to laboratory culture-based testing for the presence of microorganisms.

• Journal of Food Hygiene and Safety
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• v.36 no.4
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• pp.342-346
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• 2021

Cold brew coffee extracted from cold water for a long time has drawn public concern over hygiene. This study was carried out to investigate the microbiological contamination levels and caffeine contents in cold brew coffee. A total of 75 cold brew coffees were purchased from offline and online sources. As a result, the average number of bacteria in samples purchased online was 1.14 log CFU/mL (0-6.57 log CFU/mL), while bacteria were not detected in samples purchased offline. Therefore, stricter surveys are required to avoid the food contamination. However, Esherichia coli and nine types of foodborne pathogens were not detected in all samples. The average caffeine content of the samples was 1.6 mg/mL (384 mg/240 mL), so the caffeine almost reached to acceptable daily intake levels (400 mg for adults). However, ten products did not provide any precautions for consumer safety, so improvement of the system is needed. This monitoring data can contribute to the protection of consumer rights and improvement in the safety of cold brew coffee.

• Journal of Food Hygiene and Safety
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• v.37 no.3
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• pp.181-188
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• 2022

Despite the recent increase in the consumption level of the processed meat-byproducts, the health and safety issue has consistently been raised in the processes of production, distribution and consumption. The purpose of this study is to analyze and evaluate the microbiological hazard elements in the Korean sausage, "Sundae," to present not only the safety standard of meat by-product vendors based on HACCP (Hazard Analysis Critical Control Point), but also the quality control criteria and sanitary arrangements of small manufacturers. For the study, the microbiological hazards in 24 raw materials, 7 manufacturing processes, 40 facilities and tools, 17 workplace environment, and 12 workers were analyzed. The analysis revealed the hazardous elements in the initial stages with 6.28 and 4.07 log CFU/g of total aerobic count and coliforms, respectively, detected from the porcine blood and 3.23 log CFU/g of coliforms from the porcine small intestines. The result also showed that the total aerobic counts and coliforms in the process of mixing and filling process exceeds the standards in the hygiene guidelines by Natick with the total aerobic counts of 5.23, 5.45 log CFU/g, and the coliforms of 3.25, and 3.31 log CFU/g, respectively. Although the detected total aerobic count and the coliforms in the filling and washing rooms exceeded the standards, it was found that the total aerobic count was significantly reduced by 98% after cleaning and disinfecting and no coliforms was detected in any process thereafter. In order to achieve high level of safety in the manufacturing processes of Sundae, the separation of washing and disinfection room from the other sections and the sanitation control of the workers must be preceded, along with strict monitoring in the storage and distribution processes. The study raises necessity for additional studies for the safety evaluation of the processed meat-byproducts and further researches on the validity of the critical limits.

• Food Science and Preservation
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• v.19 no.1
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• pp.62-66
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• 2012

With the rapid growth of fresh-cut produce market, the South Korean fresh-cut industry is facing the challenge of ensuring food safety. As the estimation of the microbial numbers in fresh-cut produce processing lines (tools, and equipment) using the conventional microbiological techniques takes days, so there is a need for faster and easier monitoring methods. This study was conducted to investigate the use of ATP bioluminescence assay to measure the degree of microbial contamination from three actual fresh-cut processing lines. The samples collected from frech-cut vegetables, and fresh-cut fruits processing plants were tested for the estimation of the bacterial number, using the ATP bioluminescence and microbiological methods. The result of former was transferred to log RLU/100 $cm^2$, and that of the latter was transferred to log CFU/100 $cm^2$. A positive linear correlation between the ATP bioluminescence assay value and aerobic-plate count was found for fresh-cut processing lines, with a correlation coefficient of 0.8772 (n=50). The results of this study indicate that ATP bioluminescence assay can be used to monitor microbial contamination in fresh-cut produce processing plants, and can help improve the hygiene therein.

• Food Science and Preservation
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• v.18 no.1
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• pp.7-12
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• 2011

Paprika is a major export of Korea, but biosafety is important if exports are to grow. To date, few paprika biosafety data are available. We evaluated microbiological contamination of paprika, and determined bacterial levels with respect to storage temperature. Mean counts of total aerobic bacteria were $2.3{\pm}0.3\;log_{10}\;CFU/g$, but coliforms were not isolated. Staphylococcus aureus, Salmonella spp., Listeria spp., and Escherichia coli O157 were also not detected. When bacterial contamination of paprika stored at room temperature or $4^{\circ}C$ for 20 days was evaluated, the numbers of total aerobic bacteria peaked at 14-16 days at room temperature (4 times more than those of $4^{\circ}C$). However, aerobic bacteria grew slowly at $4^{\circ}C$. Coliforms were also detected twice at room temperature, but not upon storage at $4^{\circ}C$. The results indicate that the paprika exported from Korea is relatively biosafe. However, food hygiene issues must be addressed to reduce contamination during storage and distribution.

• Korean Journal of Microbiology
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• v.39 no.4
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• pp.253-259
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• 2003

To assess microbiological indoor air quality in kindergartens, concentrations of viable airborne microorganisms were seasonally determined at three kindergartens in Ulsan from April, 2002 to January, 2003. Sampling was performed with an impaction-type air sampler and three different media. The numbers of bacteria grown on Staphylococcus medium were between 84 and 4,150 MPN/m3 with an average of 827 MPN/m3, and those on standard method agar ranged from 50 to 2,636 MPN/m3 with an average of 580 MPN/m3. The bacterial concentrations were highest in summer, followed by fall, spring, and winter, and were significantly correlated with indoor temperature. Among the colonies, 45.6~61.0% were observed as Gram-positive cocci and 8.5~20.6% were Gramnegative rods. Micrococcus species were the dominant organisms. The numbers of fungi ranged from 0 to 1,888 MPN/m3(661 MPN/m3 average) based on colony counts with dichloran rose bengal chloramphenicol agar. On average, the fungal concentrations were highest in summer and lowest in winter. Penicillium species and Aspergillus species were identified from the colonies. The obtained data can be utilized as a step to set a guideline for bioaerosols in indoor environment of schools.