• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.5
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• pp.744-751
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• 1995

Effect of licorice root(Glycyrrhiza Uralensis Fischer) on the Dongchimi(watery radish kimchi) fermentation was investigated by measuring physicochemical, microbiological and sensory properties during fermentation up to 41 days. Dongchimi with the various levels(0, 0.5, 1.0, 1.5%) of licorice root was fermented at two temperatures : Group A was fermented at $10^{\circ}C$ and group B was fermented at $4^{\circ}C$ after keeping at room temperature($16{\pm}0.5^{\circ}C$) for 24 hours. During the fermentatiion, pH was slowly lowered in all Dongchimi samples and pH of Dongchimi added licorice root was a little higher than that of Dongchimi without licorice root. Total acidity of group A was slightly larger than that of group B and Dongchimi added licorice root showed small content than that of Dongchimi without licorice root. Reducing sugar content was reached maximum value in 13 days of fermentation in Dongchimi added licorice root of group A and B, group A decreased remarkably in 32 days of fermentation in all samples and group B was maintained in the rest sample except for Dongchimi without licorice root and Dongchimi added 1.5% licorice root. Total vitamin C of Dongchimi added licorice root was slightly higher than that of Dongchimi without licorice root of two groups. Lightness lowered gradually with the fermentation and Dongchimi without licorice root decreased a little than that of Dongchimi added licorice root. The number of lactic acid bacteria in Dongchimi added licorice root was more numerous than that of Dongchimi without licorice root. As a result of the sensory evaluation, group B showed higher scores than group A and Dongchimi added 0.5% licorice root was the most preferable one.

• Journal of Dairy Science and Biotechnology
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• v.16 no.2
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• pp.90-97
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• 1998

This study was carried out to investigate changes of microbiological and sensory properties in various heat-treated market milks (LTLT, HTST, and UHT milks) stored at 10$^{\circ}C$ during 15d. Titratable acidity (TA) increased with storage, while pH tended to decrease. During the initial 9d, no difference was found in TA, however, after 9d, it was slightly higher in HTST and UHT milks than that in LTLT milk. In LTLT and HTST milks, total viable cells and psychrotrophs were dramatically increased during storage, In addition coliform and pathogenic bacteria were found at 12 and 15d. In UHT milk, total viable cells were found only at 15d. In sensory evaluation, LTLT and HTST milks developed a negligible off-flavor until 9d. At 12d, it became stronger in HTST milk than that in LTLT milk. In UHT milk, off-flavor was detected at 9d and increased rapidly there-after. The degree of off-flavor was little higher in HTST and UHT milks, compared with that of LTLT milk after 9d storage. These observations indicated that LTLT and HTST milks may not be microbiologically acceptable after 5d, while off-flavor was not detectable until 9d, In comparison, UHT milk keeps a good quality in microorganism until 15d, however, it may not be accepted in sensory aspect after 9d storage.

• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.272-278
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• 2013

To evaluate the effect of surface contaminated with Escherichia coli O157:H7 (E. coli O157:H7) on the microbiological safety of lettuce, this study was conducted to investigate the attachment, biofilm producing, survival, and cross-contamination of E. coli O157:H7 on stainless steel and polyvinyl chloride (PVC). The attachment rate of E. coli O157:H7 on PVC was 10 times higher than that on stainless steel after exposure 1 h in cell suspension. However, there was not a difference between two types of surface after exposure for 6 h and 24h. The biofilm producing of E. coli O157:H7 was TSB > 10% lettuce extracts > 1% lettuce extracts > phosphate buffer. When two kinds of materials were stored at various conditions ($20^{\circ}C$ and $30^{\circ}C$, relative humidity (RH) 43%, 69%, and 100%), the numbers of E. coli O157:H7 at $30^{\circ}C$, RH 43% or RH 69% were reduced by 5.0 log CFU/coupon within 12 h regardless of material type. Conversely, the survival of E. coli O157:H7 at RH 100% was lasted more than 5 days. In addition, the reduction rate of E. coli O157:H7 was decreased in the presence of organic matter. The transfer efficiency of E. coli O157:H7 from the contaminated surface to lettuce was dependent upon the water amount of the surface of lettuce. Especially, the transfer rate of E. coli O157:H7 was increased by 10 times in the presence of water on the lettuce surface. From this study, the retention of E. coli O157:H7 on produce contact surfaces increase the risk cross-contamination of this pathogen to produce. Thus, it is important that the surface in post harvest facility is properly washed and sanitized after working for prevention of cross-contamination from surface.

• Korean Journal of Microbiology
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• v.35 no.4
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• pp.307-314
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• 1999

This study was aimed at the investigation of the possibility of the addition of lactic acid bacteria as "starter"for the preparation of radish juice. Forty strains of lactic acid bacteria were isolated from dongchimi that was fermented by a traditional method. The isolates were assorted into 5groups, Leuconostoc mesenteroides subsp. mesenteroides (J-9), Lacobacillus brevis (J-12), Lactobacillus fermentum (J-7), Lactobacillus sake (J-20), and Lactobacillus plantarum (J-39). Leuconostoc mesenteroides was predominated in the sample of dongchimi with frequency of 52.5%. Each of the strain, which exhibited the beat growth in the species, was selected in the 5species, and investigation of the fermentation characteristcis was carried out. The fermentation were performed for 9 days at 25${\circ}C$ after the inoculation of 0.3% ($10^{6}$ cfu/㎖) to each ultra-filtrated radish juice. The pH, total acidity, content of non-volatile organic acids were examined during the fermentation period. Lactobacillus plantarum showed the highest growth rate and the growth rate of Lactobacillus sake was the lowest. The pH (6.3-6.36) and total acidity (0.09-1.0 %) fo the ultrafiltrated radish juice before fermentation were changed to 3.2-4.3 and 0.65-1.2% after 9days, respectively. The changes of the pH and total acidity were related with the growth of the lactic acid bacteria; the better growth of lactic acid bacteria, the more rapid decrease of pH and increase of the total acidity. when the amount of non-volatile organic acids were estimated during fermentation, citric acid, malic acid, malonic acid, and succinic acid were decreased in all cases. However, the content of lactic acid increased with the progression of fermentation. L. mesenteroides (J-9), L. brevis (J-12) and L. fermentum (J-7) were chosen for the candidates of the starter for the lactic fermentation of radish juice based on the biochemical analysis and sensory evaluation.

• Korean Journal of Microbiology
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• v.49 no.1
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• pp.64-70
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• 2013

The greenhouse whitefly, Trialeurodes vaporariorum, is an economically important pest for greenhouse crops because they cause direct damage by feeding on plant nutrients and indirect damage as transmits many virus vectors. It has recently become a serious problem because of the continuous use of insecticide resulting in resistance among greenhouse whitefly population. To overcome these problems, in this study, the biological characteristics and virulence of an entomopathogenic fungus isolated from the cadaver of nymph greenhouse whitefly were investigated. Isolated fungus was identified as Isaria fumosorosea by morphological examinations and genetic identification using sequences of the ITS, ${\beta}$-tubulin, and EF1-${\alpha}$ regions. This fungus was named as I. fumosorosea SDTv and tested for the virulence against nymphs T. vaporariorum and the cold activity, the thermotolerance and the stability of UV-B irradiation on conidia. Mortality rate of greenhouse whitefly showed from 84 to 100% and the virulence increased with increasing conidial concentrations, $1{\times}10^5$ to $10^8$ conidia/ml. Conidia were stable at $35^{\circ}C$, 0.1 $J/cm^2$ of UV irradiation and germinated after 8 days at $4^{\circ}C$. Additionally, the activities of chitinases and proteases produced by I. fumosorosea SDTv were varied according to the medium. In conclusion, I. fumosorosea SDTv which showed high mortality rate against greenhouse whitefly will be used effectively in the integrated pest management programs against the greenhouse whitefly.

• Food Science and Preservation
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• v.15 no.6
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• pp.909-914
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• 2008

This study investigated microbial populations and the sensory quality of sikhae including globefish (GLS), flounder (FLS), gastropods (GAS) and whelks (WHS) during storage at 4C for 16 d following fermentation at 10C for 4 d. General bacterial numbers increased to 102 in GLS and FLS, and to 1045 in WHS and GAS after the 20 d fermentation/storage period. Lactic acid bacteria increased to 108 log cycle in GLS and FLS after 10 d ripening time, and reached this level in GAS and WHS after 15 d and 20 d, respectively. After 20 days the number of lactic acid bacteria in each of the four samples was 108. There were 104105 yeast cells/g in each of the four samples after 20 d. The number of Leuconostoc increased to over 108 log cycle after 10 d in GLS and FLS, and 15 days in GAS for WHS the increase was to 107 log cycle. The pH values of GLS, FLS, GAS and WHS 4.42, 4.56, 4.31 and pH 4.26, respectively. The Sikhae acidity for all four samples ranged from 1.551.85%. From the sensory evaluation the overall acceptability was in the order of FLS > GLS > GAS > WHS.

• Korean Journal of Microbiology
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• v.52 no.4
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• pp.455-462
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• 2016

Pseudomonas aeruginosa P-5 is an unusual organism capable of synthesizing polyhydroxyalkanoates (PHAs) consisting of 3-hydroxyvalerate (3HV) and medium-chain-length (MCL) 3-hydroxyalkanoate (3HA) monomer units when C-odd alkanoic acids are fed as the sole carbon source. Evaluation of the substrate chain-length specificity of two P. aeruginosa P-5 PHA synthases ($PhaC1_{P-5}$ and $PhaC2_{P-5}$) by heterologous expression of $PhaC1_{P-5}$ and $PhaC2_{P-5}$ genes in Pseudomonas putida GPp104 revealed that $PhaC2_{P-5}$ incorporates both 3HV and MCL 3HAs into PHA, whereas $PhaC1_{P-5}$ favors only MCL 3HAs for polymerization. In order to obtain $PhaC2_{P-5}$ mutants with altered substrate specificity, site-specific mutagenesis for $PhaC2_{P-5}$ was conducted. Amino acid substitutions of $PhaC2_{P-5}$ at two positions (Ser326Thr and Gln482Lys) were very effective for synthesizing copolymers with a higher 3HV fraction. When recombinant P. putida GPp104 harboring double mutated $phaC2_{P-5}$ gene ($phaC2_{P-5}QKST$) was grown on nonanoic acid, 2.5-fold increase of copolymer content with 3.8-fold increase of 3HV fraction was observed. The $phaC2_{P-5}QKST$-containing Ralstonia eutropha PHB-4 supplemented with valeric acid also produced copolymers consisting of 3HV and 3-hydroxyheptanoate with a high 3HV fraction. These results suggest that recombinants containing $phaC2_{P-5}QKST$ could be useful for production of new PHA copolymers with improved material properties.

• Tuberculosis and Respiratory Diseases
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• v.53 no.4
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• pp.389-400
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• 2002

Background : The rapid diagnostic tests for tuberculosis are needed to facilitate early treatment of tuberculosis and prevention of Mycobacterium tuberculosis transmission. The Xeniss Rapid TB kit is a rapid, card-based immunochromatographic test for the detection of antibodies directed against M. tuberculosis antigens including antigen 5(38-kDa antigen). The objective of this study was to evaluate the performance of the Xeniss Rapid TB kit for the diagnosis of active tuberculosis with serums from patients, asymptomatic healthy and close contact controls. Methods : 188 patients with active tuberculosis were tested; 177 with pulmonary tuberculosis(18 with combined pleurisy), and 11 with extrapulmonary tuberculosis. The control groups were composed of 82 close contacts and 57 healthy adults. Study subject were drawn from one national tuberculosis hospital for patients and close contacts, and another private hospital for healthy adults in Masan city, Korea. The Xeniss Rapid TB kit(Xeniss Life Science Co., Ltd., Seoul, Korea) was evaluated by using serum samples according to the instructions of the manufacturer by an investigator masked to the clinical and microbiological status of the study subjects. Results : The diagnostic sensitivity of the Xeniss Rapid TB kit was 73.9% in patients and specificities were 73.2% and 93.0% in close contact and healthy adults respectively. The positive predictive value in patients was 84.2% and the negative predictive value in controls was 85.8%. Conclusion : This study shows that the Xeniss Rapid TB test is a simple and fast method to diagnose active TB. The results of the sensitivity and specificites suggest that serodiagnosis using this point of care testing(POCT) device would be valuable and advantageous for screening tuberculosis in the clinical field.

• Journal of Food Hygiene and Safety
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• v.4 no.2
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• pp.119-132
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• 1989

Gamma irradiation as a new physical treatment was applied to comparative investigates with a conventional ethylene oxide fumigant on the microbiological and physicochemical qualities of selected spices and dry vegetables such as powdered red pepper, black pepper, welsh onion, onion, garlic, carrot, korean cabbage and instant ramyon soup. The microorganisms contaminated in the sample, including total viable count, thermophilic bacteria, aerobic spore and fungi counts between the $10^4\;to\;10^6/g$ range. Coliforms were found only in black pepper and welsh onion powder as the $10^2\;to\;10^3/g$ level. A radiation dose of 7 to 10 KGy were sterilized completely to the contaminated microorganisms, while ehthylene oxide (E.O.) fumigation reduced of them to the $10^3/g$ level. An optimum dose of irradiation was less detrimental than E.O. fumigation to the physicochemical properties of the sample. Sensory evaluation after three months of storage at room temperatures showed that the overall acceptability of irradiated sample was higher than that of the non treated control as well as E.O. fumigated samples. Comparison gamma irradiation with E.O. gas treatment showed that E.O. treatment was less effective than radiation in cotrolling microbial contamination of spices and vegetables.

• Korean Journal of Microbiology
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• v.48 no.4
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• pp.314-318
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• 2012

Most types of collagen used for biomedical applications, such as cell therapy and tissue engineering, are derived from animal tissues. Therefore, special precautions must be taken during the production of these proteins in order to assure against the possibility of the products transmitting infectious diseases to the recipients. The ability to remove and/or inactivate known and potential viral contaminants during the manufacturing process is an ever-increasingly important parameter in assessing the safety of biomedical products. The purpose of this study was to evaluate the efficacies of the 70% ethanol treatment and pepsin treatment at pH 2.0 for the inactivation of bovine viruses during the manufacture of collagen type I from bovine hides. A variety of experimental model viruses for bovine viruses including bovine herpes virus (BHV), bovine viral diarrhea virus (BVDV), bovine parainfluenza 3 virus (BPIV-3), and bovine parvovirus (BPV), were chosen for the evaluation of viral inactivation efficacy. BHV, BVDV, BPIV-3, and BPV were effectively inactivated to undetectable levels within 1 h of 70% ethanol treatment for 24 h, with log reduction factors of ${\geq}5.58$, ${\geq}5.32$, ${\geq}5.11$, and ${\geq}3.42$, respectively. BHV, BVDV, BPIV-3, and BPV were also effectively inactivated to undetectable levels within 5 days of pepsin treatment for 14 days, with the log reduction factors of ${\geq}7.08$, ${\geq}6.60$, ${\geq}5.60$, and ${\geq}3.59$, respectively. The cumulative virus reduction factors of BHV, BVDV, BPIV-3, and BPV were ${\geq}12.66$, ${\geq}11.92$, ${\geq}10.71$, and ${\geq}7.01$. These results indicate that the production process for collagen type I from bovine hides has a sufficient virus-reducing capacity to achieve a high margin of virus safety.