• Journal of agriculture & life science
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• v.43 no.6
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• pp.77-84
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• 2009

Using recombinant DNA technology, the vector system containing minimal fragment of a bacterial hemoglobin gene (vgb) was constructed. When this vector was inserted into Escherichia coli, the growth of the host was significantly improved in both viable cell counts and absorbance measurement, compared to that of the wild type strain. In addition, by minimizing the size of bacterial hemoglobin in the vector, the ability of vgb in growth improvement was augmented, due to the reduction of metabolic burden from the maintenance and replication of the plasmid. By using this system, it is expected that the growth of microorganisms can be improved even in the hypoxic condition.

• Microbiology and Biotechnology Letters
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• v.28 no.2
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• pp.117-123
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• 2000

The object of this work is to improve the maintenance of bioluminescence from stored Photobacterium phosphoreum in a view of developing continuous monitoring system for pollutants. The long-term experiments were performed to determine the effect of storage temperature and immobilization on the maintenance of bioluminescence and viability of P. phosphoreum. A naturally luminescent bacterium, P. phosphoreum was starved in 2.5% Nael solution at $20^{\circ}C$, $4^{\circ}C$, -$20^{\circ}C$ and -$70^{\circ}C$ for 30 days. In vivo luminescence was measured by luminometry, and total cell concentrations and concentrations of culturable and viable cells were determined by acridine orange staining, dilution plate counting, and direct viable counting, respectively. The bioluminescence emission from cells stored at 4De was maintained up to 10 days while those with starved cells at other temperature ranges decreased to background level within 3 days. In terms of viability of cells, concentrations of cells stored at $20^{\circ}C$ were rapidly decreased as a result of cell lysis, leading to a drop in culturable and viable counts while cells stored at $4^{\circ}C$ was shown viable but nonculturable state during starvation. With immobilized cells on strontium alginate, the bioluminescence showed higher maintenance than free cells and decreased with count number of nonculturable cells.

• Microbiology and Biotechnology Letters
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• v.37 no.3
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• pp.258-265
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• 2009

A study on livestock environment improving agents was conducted; top two brands (A and B) in the market, bottom two brands (E and F) based on market shares and two newly developed agents (C and D) were measured for viable count and tested for resistance towards antibiotics prohibited against livestock feeds. Test results revealed that the measured viable count of agents A and B matched those on the labels were identical; however agent E lacked information on viable counts nor the intended usage, while the measured viable count of agent F was less than the label-stated count. No correlation was found between the antibiotic-resistance test and market share, and most of the agents excluding B were found to display resistance case of Lincosimides such as Lincomycine and Clindmycin, resistant bacteria were found, with the except of agent B. Amoxicillin, Ampicillin and Penillin (type-Penecillins) and Erythromycin (type-Macrolide) were shown to contain resistant bacteria, with the except of agents Band E; the same for Norploxacin (type-Quinoline) and Neomycin antibiotics. Aminoglycosides such as Gentamycin and Streptomycin contained resistant bacteria, excluding agent B. Oxytetracyclin (type-Tetracycline), which is banned for use as resistant bacteria showed the highest sensitivity among the 12 antibiotics, revealed positive results in the test for resistant bacteria; again excluding of agents Band E. These results reveal that many agents contained resistant bacteria despite the fact that they were prohibited; this calls for a more accurate display of the facts and specifications, systematic distributions and strict verification processes of environment improving agents.

• Food Science and Preservation
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• v.24 no.5
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• pp.576-584
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• 2017

With the goal of developing a new functional fermentation milk using green tea powder (GP), milk was fermented with direct vat set (DVS) starter culture containing Streptococcus salivarius subsp. thermophilus, Lactobacillus paracasei and L. delbrueckii subsp. bulgaricus. We investigated fermentation characteristics and antioxidative activities of fermented milk supplemented with different concentrations (0.5, 1, 2, 3%) of GP. All samples were evaluated for pH, total acidity, viable cell count, and sugar contents. The pH of all samples decreased during fermentation, and the final pH ranged from 4.35 to 4.51. The acidity increased during fermentation, after the fermentation was completed, the titratable acidity was 0.8 to 1.1%. And viable cell count of all samples increased during fermentation, and the final viable cell count was 8.57 to 8.89 log CFU/mL. The sugar content decreased as the fermentation proceeded and finally reached 12 to $13^{\circ}Brix$. And increasing GP, decreased brightness and increased yellowness. Increasing GP concentration added to milk, improved DPPH free radical scavenging activity and ferric ion reducing activity of fermentation milk. The fermentation milk kept their pH, total acidity and viable cell counts standard of fermentation milk during the storage period at $4^{\circ}C$. These findings confirmed the possibility of development of the novel functional fermentation milk through the investigation of the quality characteristics of the fermentation milk added with GP.

• Microbiology and Biotechnology Letters
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• v.43 no.1
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• pp.31-37
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• 2015

This study was conducted to investigate the bactericidal activity of electrolyzed water (EW) against coliform bacteria on Undaria pinnatifida (UP). The UP was washed with 15% EW, tap water (TW), and distilled water in the following order: 15% EW for 5 and 10 min (1st to 3rd washing process), TW for 1 min, and distilled water for 10 min (3rd to 5th washing process). The washing processes using 15% EW and distilled water occurred a total of 6 times. The number of viable cells, coliform bacteria, and molds in the untreated sample were in the range of 10¹ to 10³ CFU/g. In the case of the UP with 15% EW for 5 min sample, the viable cell counts were reduced by 1-2 log cycles as compared with the untreated sample. The coliform bacteria were not detected except after the 1st EW washing process. Mold counts were not detected in all treatments. In the UP with 15% EW for 10 min sample, the viable cells, coliform bacteria, and mold counts were not detected. In color, there were no significant differences among samples. In sensory evaluation, the UP treated with 15% EW for 10 min (first washing process) got higher scores for color, aroma, and taste than others. These results suggest that the treatment of 15% EW for 10 min is the most effective way to reduce coliform bacteria of the UP.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.667-676
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• 2004

Yogurt was prepared from skim milk added with 1, 2, 4 or 6% of rice- or skim milk powders and commercial lactic acid bacterial starters. Changes in pH, titratable acidity, viable cell counts, viscosity, organic acid contents and carbohydrates during fermentation were monitored and its sensory evaluation was also performed. The optimum level of additives such as rice- and skim milk powders for yogurt manufacture was selected. Fermentation properties of yogurt added with rice and skim milk powders were studied. The control yogurt reached pH 4.5 after 10 hours of fermentation, whereas the samples added with 4 or 6% rice powders reached pH 4.5 in 6 hours and those added with skim milk powder reached in 8 hours. After 4 hours of fermentation, the control yogurt reached a titratable acidity at 1.0 %, whereas other samples exceeded 1.0%. After 4 hours of fermentation, the viable cell counts in the samples added with 4% rice powders were the highest. At the level of 4% rice powders, the curd viscosity decreased. Except for the sample added with 6% skim milk powders, all the samples produced higher lactic acid during fermentation, and galactose level in yogurt was the highest when added with 4% rice powder or 6% skim milk powder. In overall sensory evaluation using 5 parameters, the sensory scores of all the yogurts were not significantly different. However, the sample added with 4% skim milk powders was the best for color and overall acceptability. The sample added with 4% rice powders was the best for the flavor and texture. From this experiment, the optimun level of additives such as rice or skim milk powders was selected to be 4%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.4
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• pp.611-616
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• 2001

Effects of high pressure and thermal pasteurization on the survival of microorganisms and quality changes of kochujang during 120 days of storage at 37$^{\circ}C$ were investigated. Viable cell counts were 1.43$\times$10$^{6}$ CFU/g in heat-treated, and 1.56$\times$10$^3$ CFU/g in pressure-treated, and decreased up to 3 log cycle, compared with 3.78$\times$10$^{6}$ CFU/g in the untreated kochujang. Viable cell counts decreased by the storage period at 37$^{\circ}C$. Viable cell counts decreased up to 2 log cycle from 3.78$\times$10$^{6}$ to 5.43$\times$10$^4$ CFU/g in the untreated kochujang, 4 log cycle from 1.43$\times$10$^{6}$ to 3.10$\times$10$^2$ CFU/g in heat-treated after 120 days of storage, while those in pressure-treated were not detected after 90 days from the initial stage of 1.56$\times$10$^3$ CFU/g. pH decreased significantly by the storage time. Titratable acidity increased significantly during storage, and pressure-treated kochujang showed lower values than heat-treated. Amino nitrogen content decreased significantly during storage, and pressure-treated kochujang showed higher values than heat-treated and lower values than the untreated. There were no significant changes in reducing sugar and ethanol content regardless of the treatment condition and the storage period. Hunter L, a and b values decreased significantly during storage. In the untreated kochujang, the changes in color accelerated compared with heat and pressure-treated.

• Journal of Life Science
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• v.19 no.4
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• pp.486-491
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• 2009

This study was conducted to investigate microbial distribution in the processing steps and to estimate quality index and shelf life of packaged Tofu (soybean curd). Sanitation and safety of Tofu were analysed in aspects of total viable counts (TVCs) and coliforms. Organoleptic deterioration was observed from some packaged Tofu when their TVCs were over $10^6\;CFU/g$. The controlled simply packaged Tofu and sterilized Tofu with TVCs of under $10^5\;CFU/g$ were 32.0% and 86.9% of the total samples, respectively. Also, the controlled simply packaged Tofu and sterilized Tofu with negative coliforms were 12.0% and 83.7% of the total samples, respectively. TVCs and coliforms increased in some processing steps, which include washing and soaking of raw soybeans, and formation and 1st cooling of packaged Tofu. Increases of TVCs and coliforms in the washing and soaking step were due to contamination from the soaking tank and airborne bacteria, whereas increases of TVCs and coliforms in the grinding step were due to contaminations from the grinder, line and reserving tank. TVCs and coliforms increased in the formation and 1st cooling step of packaged Tofu due to contaminations from filter wools, trays, employee's hands, cooling water, formed products and filter wools.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.150-155
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• 2016

This study investigated the effects of combined treatments of immersion liquid and high hydrostatic pressure (HHP, 100−400 MPa) on the quality of mackerel. In this study, we measured viable cell counts, pH level, color value, texture properties, and sensory evaluation of mackerel. Viable cell counts of mackerel treated with combined HHP were decreased by 2 log cycles at 300 MPa and 400 MPa compared to the control. The pH values of mackerel treated with HHP at 300 MPa and 400 MPa were higher than that of other samples. Hardness, gumminess, and chewiness decreased when treated with combined HHP and increased with increase in HHP. Lightness and whiteness of mackerel increased, but redness decreased, with increase in HHP. In case of sensory evaluation, texture of mackerel treated with HHP at 300 MPa and 400 MPa showed higher scores than that of other samples. These results suggest that immersion liquid and HHP treatments can increase microbiological safety and improve textural properties of mackerel.

• Korean Journal of Food Science and Technology
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• v.47 no.6
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• pp.765-771
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• 2015

This study was performed to examine the quality characteristics and antioxidant activity of the curd yogurt with different contents (0.5-2%, w/w) of acanthopanax powder (AP). The pH decreased with increasing AP content until 16 h, whereas the treated groups showed higher pH levels than the control group after 20 h. The viscosity and the viable cell counts of the yogurt with 2% AP were lower than those of the control group during fermentation, significantly. Color values of AP yogurt were lower in terms of brightness, whereas redness and yellowness values were higher compared to the control group. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and soluble content significantly increased with increasing AP content. Consumer acceptability score of yogurt with 0.5% AP was ranked higher than other yogurts. Yogurt added with 0.5% AP showed no differences in pH, titrable acidity, and viable cell counts compared to the control group after storage at $4^{\circ}C$ for 14 days.