• Journal of Food Hygiene and Safety
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• v.29 no.4
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• pp.268-277
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• 2014

This study assessed microbiological hazards at postharvest stage of dropwort farms (A, B, C, D, E, F, G, H, I) located in 4 different areas in Korea. The samples were assessed for sanitary indication bacteria (total aerobic bacteria, coliform, and Escherichia coli) and pathogenic bacteria (Escherichia coli O157:H7, Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus). Total aerobic bacteria and coliform in 9 dropwort farms were detected at the levels of 0~7.00 and 0~4.25 log CFU/g, mL, of $100cm^2$. In particular, microbial contamination in worker's hand showed higher than cultivation environment factors. Escherichia coli was detected in several farms of soil, irrigation water, washing water and worker's hand and also, dropwort in these farms was contaminated with E. coli (positive reaction). In case of pathogenic bacteria, B. cereus was detected at the highest levels in soil. S. aureus was detected qualitatively from only one sample of dropwort washed by water. E. coli O157:H7 and L. monocytogenes were not detected. Although dropwort pass through 2 process (trimming and washing), the microbial contamination was not differ significantly before and after which indicates that current washing system was not effect on reduction of microorganism. From these results, the postharvest environment and workers have been considered as cross-contamination factors. Thus, processing equipments and personal hygiene should be managed to reduce the microbial contamination of dropwort. Accordingly management system such as good agricultural practices (GAP) criteria is needed for the safety of dropwort

• Journal of Applied Biological Chemistry
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• v.57 no.1
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• pp.83-87
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• 2014

The effects of combined treatment of aqueous chlorine dioxide ($ClO_2$) and fumaric acid on the microbial growth in fresh-cut paprika were investigated. After the combined treatment, the populations of total aerobic bacteria and inoculated Listeria monocytogenes in the paprika sample were reduced by 0.82 and 1.21 log CFU/g, respectively, compared to those of the control. In addition, after 10 d of storage at $10^{\circ}C$, the populations were decreased by 1.21 and 2.10 log CFU/g, respectively. The predictive model for the populations of total aerobic bacteria and L. monocytogenes in the paprika was applied during storage. The prediction equation using Gompertz model was appropriate, based on the statistical analysis such as accuracy factor and bias factor. These results suggest that the combined treatment of aqueous $ClO_2$ and fumaric acid can be an effective technology for microbial decontamination and it can improve microbial safety by decreasing maximum growth rate and increasing lag time of bacteria in the fresh-cut paprika.

• 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.17 no.1
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• pp.23-29
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• 2010

The effects of vinegar, alcohol, and vitamin C on the color, microorganism count, volatile flavor components, free sugar level, free amino acid concentration, and free fatty acid level of minced ginger were investigated during storage for 17 weeks at $10^{\circ}C,\;20^{\circ}C\;or\;30^{\circ}C$. Bacterial levels remained unchanged during storage and mold was not initially detected. Yeast levels in minced ginger were $5{\times}10^1$ CFU/g initially, and yeast was not detected after 2 weeks. The color values increased during storage at high temperature. The volatile flavor component levels decreased during high-temperature storage. The free sugars of minced ginger were glucose, sucrose, and fructose. Sugar levels did not vary greatly with storage temperature. Free amino acid content decreased during high-temperature storage, and glutamine, valine, alanine, asparagine, tyrosine, and leucine were detected. Free fatty acid content increased during storage and the ratio of unsaturated to saturated fatty acids was 3:7.

• Korean Journal of Food Science and Technology
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• v.33 no.3
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• pp.327-332
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• 2001

Attempts were made to investigate the effect of gamma irradiation and heat treatment on quality changes of Bulgogi sauce during the storage at 4 and $20^{\circ}C$. Total acidity, Surface color, brix, microbial growth and sensory quality of test products were evaluated during storage. Total acidity of sauce did not change during storage at $4^{\circ}C$, whereas those of control and 4 kGy groups changed significantly during storage at $20^{\circ}C$. Gamma irradiation and heat treatment had little effect on brix of the suace during storage period. Surface color of control and 4 kGy group significantly changed during storage, especially at $20^{\circ}C$. Sucrose contents in sauce decreased during storage, while glucose and fructose contents increased. Sensory quality of sauces stored at $4^{\circ}C$ for 12 weeks was similar, except the control. Control and 4 kGy treated sauces stored at $20^{\circ}C$ for 6 week had detectable levels of off-flavor. Colifrom bacteria were not detected in sauces treated by either heat or gammma-ray. Total acrobic increases in colony counts were slower at $4^{\circ}C$. Yeasts or molds were not detected in sauces treated by heat or gamma-ray over 7-10 kGy. These results indicated that gamma irradiation over 7kGy or heat treatment of the sauce maintained acceptable quality.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.4
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• pp.450-458
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• 2017

In this study, the antimicrobial activity of black garlic pomace extract (BGPE) was examined, and its washing applicability to spinach was investigated. BGPE had antimicrobial activity against both Gram-positive (Listeria monocytogenes and Staphylococcus aureus) and Gram-negative (Escherichia coli O157:H7 and Salmonella Typhimurium) food-borne pathogens. In particular, antimicrobial activities of BGPE against Gram-positive bacteria were higher than those against Gram-negative bacteria. Spinach samples were treated with 0.5% BGPE to determine the effect of BGPE on reducing naturally existing microorganisms on the surface of spinach leaves. BGPE treatment reduced populations of total aerobic bacteria and yeast/molds in spinach by 1.23~1.35 log CFU/g and 0.82~1.12 log CFU/g during 9 days of storage, respectively, compared with those of control samples. After treatment, there were no significant differences in color quality such as Hunter L, a, and b values and total color difference (${\Delta}E$). These results clearly indicate that BGPE treatment can be useful for improving microbiological safety and maintaining color quality of spinach during storage.

• Journal of Life Science
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• v.26 no.2
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• pp.265-274
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• 2016

Toxin-antitoxin (TA) systems are ubiquitous genetic modules that are evolutionally conserved in bacteria and archaea. TA systems composed of an intracellular toxin and its antidote (antitoxin) are currently classified into five types. Commonly, activation of toxins under stress conditions inhibits diverse cellular processes and consequently induces cell death or reversible growth inhibition. These effects of toxins play various physiological roles in such as regulation of gene expression, growth control (stress response), programmed cell arrest, persister cells, programmed cell death, phage protection, stabilization of mobile genetic elements or postsegregational killing of plasmid-free cells. Accordingly, bacterial TA systems are commonly considered as stress-responsive genetic modules. However, molecule screening for activation of toxin in TA system is available as development of antimicrobial agents. In addition, cytotoxic effect induced by toxin is used as effective cloning method with antitoxic effect of antitoxin; consequently cells containing cloning vector inserted a target gene can survive and false-positive transformants are removed. Also, TA system is applicable to efficient single protein production in biotechnology industry because toxins that are site-specific ribonuclease inhibit protein synthesis except for target protein. Furthermore, some TA systems that induce apoptosis in eukaryotic cells such as cancer cells or virus-infected cells would have a wide range of applications in eukaryotes, and it will lead to new ways of treating human disease. In this review, we summarize the current knowledge on bacterial TA systems and their applications.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.244-253
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• 2012

The effect of fermented Rhus verniciflua stem bark (FRVSB) extract on the microbial count, enzyme activity, concentrations of free amino acids and organic acids, and physiochemical properties of doenjang (soybean paste) was evaluated during brine fermentation. The FRVSB extract increased the total free amino acid concentration by 1.3-3.1-fold on the $42^{nd}$ day of brine fermentation. After the filtration of brine, the following microbial counts were obtained in the doenjang: bacteria, $0.3{\times}10^8-12.0{\times}10^8$ cfu/g; mold, $3.0{\times}10^4-21.0{\times}10^4$ cfu/g; yeast, $1.0{\times}10^4-2.0{\times}10^4$ cfu/g; Escherichia coli, not detected; and Bacillus cereus, $3.0{\times}10^2-25.0{\times}10^2$ cfu/g. The FRVSB extract addition enhanced the protein and starch degrading activity by 13.8-26.0% and 16.1-35.1%, respectively. The extract increased the total free amino acid content by 1.4-3.0-fold. Lactic acid, acetic acid, and pyroglutamic acid were the predominant organic acids in doenjang. Moreover, the proximate composition, pH, moisture, ash, salt, and amino nitrogen content were increased.

• Pediatric Infection and Vaccine
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• v.30 no.2
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• pp.84-90
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• 2023

Purpose: Infants aged ≤90 days with fever are susceptible to severe infections. This study aimed to analyze the clinical features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in this particular age group. Methods: Infants aged ≤90 days who were diagnosed with coronavirus disease 2019 (COVID-19) and hospitalized between March 1, 2020, and May 1, 2022 were included. Medical records of patients were retrospectively reviewed. Results: A total of 105 infants with COVID-19 were included; 27 (25.7%) neonates aged <28 days, and 48 (45.7%) and 30 (28.6%) infants aged 28-59 days and 60-90 days, respectively. Five (4.7%) patients remained asymptomatic and 68 (62.8%) were febrile, with a median fever duration of 2 days. The most common symptoms were respiratory including cough (66.6%), nasal stuffiness (51.4%), and rhinorrhea (40.9%). Blood cultures were performed in 10 infants but no organisms were detected. Cultures of bag-collected urine specimens from 8 infants were grown, resulting in positive growth for 2 without pyuria. Nine (8.6%) infants were treated with empirical antibiotics for a median duration of 2.3 days (range, 1-7 days). All 105 infants showed improvement without any complications, and there were no fatal cases. Conclusions: In this study, most infants aged ≤90 days with COVID-19 presented with mild symptoms and none of those evaluated had documented bacterial co-infection. The favorable prognosis among young infants with SARS-CoV-2 may aid clinicians in tailoring their approach to evaluation and management during outbreaks.

• The korean journal of orthodontics
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• v.29 no.3 s.74
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• pp.361-374
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• 1999

Intraoral filled type of orthodontic appliance can cause reversible or irreversible damages such as gingivitis, periodontitis, enamel decalcification, dental caries, root resorption, and pulpal changes. Such adverse effects are brought by increase in dental plaque as well as oral flora. Such an increase causes gingival inflammation and enamel decalcification. The purpose of this study is to get klowledge on initial changes in dental plaque, gingivitis, and enamel decalcification after bonding fixed orthodontic appliances according to time flow, gender, and sides(right/left) of premolar region. For control group, 48 students of dental college, Yonsei university(26 males, 22 females) were chosen; for experimental group, 73 orthodontic patients(36 males, 37 females) who will be treated with fixed appliances were chosen. All the subjects had no systemic disease, juvenile periodontitis and all the females had passed their ,menarche. Tooth brushing instruction was given to all the subjects prior to the experiment. For control group, plaque index, gingival index, and decalcification index were measured twice at 3 weeks interval ; for experimental group, the same was done prior to, 3, 6, 9 weeks after bonding fixed appliances. The following results were obtained: 1. In plaque index 3 weeks after placement of appliances, and it showed gradual increase afterwards. 2. In gingival index3 weeks after placement of appliances, and afterwards it showed increase at a faster rate than plaque index. 3. Enamel decalcification began to show between 3 and 6 weeks after bonding fixed appliances. Decalcification index began to increase 6 weeks after appliance placement, but there was no statistical significance. 4. When the comparison was made between two sides of premolar region, the right side showed greater index in plaque and gingival index of experimental group.