• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.4
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• pp.427-439
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• 2021

Objectives: This study aims to investigate differences in microbial contamination according to the duration and environment of mask wearing. Methods: Forty-five participants were recruited from workers in an offices, multi-purpose facilities, and a schools. After wearing of KF94 mask for two. four, and six hours, the microorganisms adsorbed on the outer and inner layers of the mask were inoculated on BAP(Blood Agar Plate), Chocolate agar, and SDA plates. The bacterial count (CFUs: colony-forming units) cultured in each plate was measured and analyzed for changes in filtration efficiency. Results: The microbial contamination of masks worn in classrooms, offices, and multi-purpose facilities showed a significant difference depending on the environment (p<0.000). The measured CFUs increased significantly according to the time wearing the mask. The difference between the inner and outer layers of the mask was also significant (p<0.05). However, there was no statistical difference in the filtration efficiency of the masks by duration time (p=0.515). Conclusions: Masks worn by workers in the offices, multi-purpose facilities, and schools showed an increase of microbial contamination with the amount of time wearing the mask. The results indicate that the masks used in daily life may have adverse health effects if they are worn for a long time or reused over several days without the realizing that the masks can be contaminated with biological hazards. Guidelines on the safe threshold time for mask use should be established through further research.

• Journal of the Korean Society of Food Culture
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• v.36 no.3
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• pp.325-332
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• 2021

This study sought to investigate the effects of heat-moisture treatment (HMT) and ethanol treatment (EOH) for improving the quality and storage stability of Tteokbokki Tteok. The quality characteristics were evaluated by moisture, pH, color, texture profile analysis, and observing the microbial properties after the heat-moisture treatment or ethanol treatment. As the storage period increased, the moisture content of Tteokbokki Tteok tended to decrease except for the HMT group (p<0.05) while the pH did not show significant variation except for the EOH group (p<0.05). While measuring the color, the L-value tended to increase in all groups during the storage period. The a-value and the b-value showed the highest values in the HMT group and the control (CON) group, respectively. In the texture profile analysis, all groups showed a significant tendency to increase levels of hardness and chewiness as the storage period increased (p<0.05). The HMT group showed an increase in hardness and adhesiveness, which are characteristics of the HMT treatment. The results of examining the microbial properties of Tteokbokki Tteok showed that the total microbial count in the HMT group was 4.52 on the 8^th day of storage, which was lower than the level in the CON group and the EOH group on the 4^th day of storage. Yeast and mold were not measured during the storage period. Thus the results of this study showed that when manufacturing Tteokbokki Tteok, the heat-moisture treatment of rice powder increased the storage stability by delaying microbial growth and also had positive effects on quality.

• Journal of Microbiology
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• v.41 no.3
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• pp.262-265
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• 2003

Although enumerating bacterial cells is a fundamental step in understanding microbial ecosystems in marine environments, substantial decrease in bacterial counts with increasing sample storage time hampers the accurate estimation of bacterial biomass. We compared the variations in bacterial cell numbers caused by freezing and thawing of sample bottles or slides. Bacterial counts of seawater samples frozen only once in a sampling bottle yielded approximately 95％ of the original numbers after 90 days, whereas 80％ of the original count was obtained for samples prepared on slides. Only 67％ and 58％ of the original counts were recovered in samples repeatedly frozen and thawed in bottles or on slides, respectively. The results indicated that freezing a seawater sample in a bottle increased the consistency of the epifluorescence microscopic enumeration of bacterial cells.

• Journal of the East Asian Society of Dietary Life
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• v.14 no.3
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• pp.265-274
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• 2004

To investigate the effect of cereal powders on the quality and storage characteristics of sausage, Aw, pH, microbial count, TBA value, VBN value, textual and sensory characteristics were examined. Water activity tended to decrease as storage time prolonged and all the samples showed higher Aw's than that of the control. During the storage period, pH values of all the samples decreased. L, a and b values had a tendency to decrease during the storage period. During the four weeks storage at 4$^{\circ}C$, TBA and VBN values of all the sample showed increasing tendency and were lower than those of the control. Total plate counts of bacteria, the number of lactic acid bacteria and coliform bacteria counts increased as the storage time prolonged. Texture characteristics of all samples increased up to 1 week storage and decreased subsequently. The sensory scores of all the samples decreased as the storage time prolonged.

• Food Science and Preservation
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• v.8 no.2
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• pp.151-156
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• 2001

Acetic acid solution containing calcium (AC) was added to kimchi seasonings by 10% and 205, and heat treatment at 70$\^{C}$ for 15 min was also tried, respectively. Kimchi with treated seasonings was investigated for the quality during fermentation at 10$\^{C}$. Heat treatment with 20% AC showed a retarded decrease pH than others on 10 days, but there was no great difference after 14 days. Higher titratable acidity was revealed in kimchi with AC during the fermentation. Total microbial lead and lactic acid bacterial count were generally lower in kimchi with AC. Reducing sugar content was maximum for all samples on 5 days, and then decreased thereafter. Redness of control kimchi was steadily increased during fermentation, but was lower than those of other treatments.

• Korean Journal of Environmental Biology
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• v.20 no.3
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• pp.189-196
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• 2002

The direct detection of intestinal pathogens and viruses often requires costly, tedious, and time-consuming procedures. These requirements developed a test to show that the water was contaminated with sewage-borne pathogens by assessing the hygienic quality of water based on indicator microorganisms whose presence indicates that pathogenic microorganisms may also be present. Various groups of microorganisms have been suggested and used as indicator microorganisms. Proposed and commonly used microbial indicators are total coliforms, fecal coliforms, fecal streptococci, Clostridium perfringens, heterotrophic plate count, bacteriophage, and so on. Unfortunately, most, if not all, of these indicators are not ideal because of the sensitivity and resistance to environment stresses and disinfection. However, the development of gene probes and PCR technology may give hope for the discovery of rapid and simple methods toy detecting small number of fecal pathogens in various environments.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.924-927
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• 2007

This study addresses the quality characteristics of commercial baechukimchi by analyzing its physicochemical characteristics and sensory properties in relation to fermentation time and temperature. The salinity of baechukimchi increased to 3.01% after 45 days of fermentation at 2 and $5^{\circ}C$, but decreased to 2.81% by 105 days. The pH decreased gradually at the beginning of fermentation, but decreased after 45 days. The acidity differed most between kimchi fermented at $2^{\circ}C$ (0.36%) and $5^{\circ}C$ (0.48%) at 45 days of fermentation. The vitamin C content was 8.47 mg% in kimchi fermented at both 2 and $5^{\circ}C$ on the day of initial production, then peaked after 45 to 60 days at 14.10 mg%, and decreased thereafter. The total microbial count gradually increased during the first 75 days of fermentation. The appearance and overall acceptability of baechukimchi were highest after 90 days of fermentation at $2^{\circ}C$ and after 60 days of fermentation at $5^{\circ}C$.

• Korean journal of food and cookery science
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• v.19 no.1
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• pp.72-78
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• 2003

This study was conducted to investigate the physicochemical and organoleptic characteristics and freshness of wild and cultivated Paralichthys olivaceus during storage. By the results of morphological observation, wild Paralichthys olivaceus had white abdomen, light black skin and transparent muscle, but cultivated Paralichthys olivaceus had black spotted abdomen, dark black skin and dark pink muscle. Moisture contents of wild and cultivated Paralichthys olivaceus were similar, but the lipid content was higher in cultivated Paralichthys olivaceus than that of wild Paralichthys olivaceus. Sensory scores of appearance, taste, texture and overall acceptability were higher in wild Paralichthys olivaceus than that of cultivated Paralichthys olivaceus. The reason was that lipid content was higher in cultivated Paralichthys olivaceus The freshness of cultivated Paralichthys olivaceus seemed to last shorter than that of wild one due to rapid increase of the volatile basic nitrogen content, pH and total microbial count during storage.

• Food Science of Animal Resources
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• v.18 no.4
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• pp.301-306
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• 1998

Four low fat ground beef groups containing 10% fat plus 0, 5, 10 and 20% additional cooked lod rice and a control ground beef containing 30% fat were prepared and the analysis for microbiological and oxidative stability were conducted. During 6 days of storage at 4$^{\circ}C$ microbial analysis including total plate count and coliform groups were performed and 2-thiobarbituric acid reactive substance (TBARS) absorbances were measured. The growth rate of total aerobic bacteria and coliform groups tended to increase with the increase in fat content and the amount of added cooked lod rice. Development of oxidative rancidity were not significantly different between 10 and 30% fat ground beef but among the 10% ground beef the rancidity development significantly(p<05) decreased with the in-crease in the amount of added cooked old rice. Low fat ground beef groups were not stable over 3 days during storage at 4$^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.4
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• pp.780-785
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• 1999

The effect of addition in different amounts of leek(4, 8, 12% respectively) during fermentation of kimchi was investigated. Fermentation characteristics such as pH, acidity and total reducing sugars as well as microbiological properties were determined. During fermentation, pH was more slowly lowered in kimchi added with leek than in control and titrable acidity of these kimchi was lower than that of control. Viable cells of total bacteria and lactic acid bacteria in these kimchi were higher than that of control during fermentation. Content of total reducing sugars was higher than that of control. Three kinds of reducing sugars such as fructose, glucose and galactose were detected and the dominant one appeared to be fructose. These results suggested that addition of leek seems to retard fermentation of kimchi due to their anti microbial actvity.