• Journal of the East Asian Society of Dietary Life
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• v.26 no.3
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• pp.230-236
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• 2016

The study was carried out to evaluate the quality of commercial pork and beef jerky at a market in Korea. The amount of food additives, place of origin, meat content, microbiological and physicochemical characteristics were investigated in 46 different jerky samples. Meat contents of pork and beef jerky were 75.2~94.0% and 80.0~95.6%, respectively. Food additives, including sodium nitrite, potassium sorbate, and sodium erythorbate were mainly used in jerky. Pork jerky was processed from domestic pork, and beef jerky was mostly processed from imported beef from the USA, Australia, or New Zealand. Pork jerky contained $23.82{\pm}5.74%$ moisture, $37.86{\pm}7.05%$ crude protein, $6.16{\pm}4.91%$ crude fat, and $4.6.87{\pm}1.76%$ crude ash. Beef jerky contained $26.64{\pm}5.21%$ moisture, $41.36{\pm}3.50%$ crude protein, $4.67{\pm}3.46%$ crude fat, and $7.21{\pm}1.91%$ crude ash. Water activity (Aw) of pork jerky was $0.73{\pm}0.09$ while that of beef jerky was $0.78{\pm}0.08$. Volatile basic nitrogen (VBN) content to jerky was 7.1~36.0 mg/100 g. There was no significant difference in the physicochemical composition of meat type (p<0.05). Coliform, Escherichia coli and Staphylococcus aureus were not detected in pork or beef jerky, whereas yeast and molds were detected below $1.2{\times}10^1CFU/g$ in beef jerky samples.

• Proceedings of the Microbiological Society of Korea Conference
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• 2001.11a
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• pp.39-45
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• 2001

Extremophiles are unique microorganisms that are adapted to survive in ecological niches such as high or low temperatures, extremes of pH, high salt concentrations and high pressure. These unusual microorganisms have unique biochemical features which can be exploited for use in the biotechnological industries. Due to the high biodiversity of extremophilic archaea and bacteria and their existence in various biotopes a variety of biocatalysts with different physicochemical properties have been discovered. The extreme molecular stability of their enzymes, membranes and the synthesis of unique organic compounds and polymers make extremophiles interesting candidates for basic and applied research. Some of the enzymes from extremophiles, especially hyperthermophilic marine microorganisms (growth above $85^{\circ}C$), have already been purified in our laboratory. These include the enzyme systems from Pyrococcus, Pyrodictium, Thermococcus and Thermotoga sp. that are involved in polysacharide modification and protein bioconversion. Only recently, the genome of the thermoalkaliphilic strain. Anaerobranca gottschalkii has been completely sequenced providing a unique resource of novel biocatalysts that are active at high temperature and pH. The gene encoding the branching enzyme from this organism was cloned and expressed in a mesophilic host and finally characterized. A novel glucoamylase was purified from an aerobic archaeon which shows optimal activity at $90^{\circ}C$ and pH 2.0. This thermoacidophilic archaeon Picrophilus oshimae grows optimally at pH 0.7 and $60^{\circ}C$. Furthermore, we were able to detect thermoactive proteases from two anaerobic isolates which are able to hydrolyze feather keratin completely at $80^{\circ}C$ forming amino acids and peptides. In addition, new marine psychrophilic isolates will be presented that are able to secrete enzymes such as lipases, proteases and amylases possessing high activity below the freezing point of water.

• Journal of the Korean Society of Food Culture
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• v.39 no.2
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• pp.119-126
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• 2024

This study was conducted to examine the microbiological quality indicators (total bacterial count and coliform count) and physicochemical quality indicators (pH, redness, volatile basic nitrogen [VBN] content) of meat according to various storage temperatures (-20~15℃) and packaging methods (wrap, vacuum). Based on these results, we proposed a safe consumption period. Redness, pH, and VBN content were not considered appropriate for setting the expiration date, as the redness and pH of the meat after spoilage were better than the standard values for both vacuum and wrap packaging (p<0.05). Additionally, the VBN content at 2 and 4℃ increased slightly (fresh level) until the initial time of spoilage (1.0×10⁶ colony-forming unit [CFU]/cm²) and then increased rapidly thereafter. Therefore, the results were not consistent with microbial spoilage. When the decay point was evaluated based on the presence of microorganisms, vacuum packaging extended the storage period approximately 2.5-fold when compared with wrap packaging, and the meat could be stored at 2 or 4℃ for 40 or 23 days, respectively. Therefore, to evaluate meat quality, microbial indicators should be considered first. The microbiological standards proposed in this study can be used for safety management during the distribution of meat. However, to ensure meat safety, additional investigations of appropriate indicators of freshness must be conducted.

• Korean Journal of Microbiology
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• v.50 no.4
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• pp.334-344
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• 2014

The objective of this study was to evaluate the microbiological and physicochemical characteristics, and the antagonistic activity against Helicobacter pylori ATCC 43504, of yogurt fermented with the lactic acid bacteria from Baikkimchi kept under cold storage. The viable cell counts, titratable acidity, viscosity, and total solid content of the yogurt were different according to the bacterial strains used for fermentation. There was no significant change (P>0.05) in the various properties of refrigerated yogurt. Among the tested strains, the strongest resistance against artificial gastric juice and bile salt was found for Lactobacillus brevis BK11 and Lactobacillus paracasei BK57. Due to high lactic acid levels obtained from these two lactic acid bacteria, yogurt may show good anti-Helicobacter effects according to the time-kill assay. In particular, yogurt fermented with L. brevis BK11 significantly reduced the number of H. pylori adhering to gastric epithelial AGS cells and the urease activity of this pathogen (P<0.05).

• Journal of the Korean Society of Food Science and Nutrition
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• v.28 no.5
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• pp.1076-1081
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• 1999

Physicochemical, microbiological, and sensory properties of barleys irradiated by gamma ray at 1.2kGy, 10.1kGy, or 30.5kGy were investigated every 40 days during the storage at 25℃ and 50% relative humidity. Moisture content of the irradiated barleys decreased but crude lipid content increased during the storage. TBA values increased in proportion to the irradiation dose and to the storage period. In Hunter's color, L, a, and b values of 30.5kGy dose irradiated barleys were higher than those of the non irradiated barleys right after irradiation and this trend continued during the storage. Numbers of mesophilic and psychrophilic bacteria in the non irradiated barleys and 1.2kGy dose irradiated barleys were higher than those in the barleys irradiated at 10.1kGy and 30.5kGy during the storage. Numbers of yeasts and molds in the irradiated and non irradiated barleys were low and they did not greatly increase during the storage. In sensory evaluation, acidic odor of the barleys was strong at the 10.1kGy and 30.5 kGy dose irradiation but barley odor and humid odor were not significantly different among the groups depending upon the radiation dose and storage period.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.11
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• pp.1843-1847
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• 2013

This study is carried out to sanitize rape (Brassica napus) pollen by gamma irradiation. Rape pollens were treated with 0, 5, 10 and 15 kGy gamma irradiations, and then analyzed for the following: general composition, microbial population, reducing sugar, Hunter color values, TBARS (2-thiobarbituric acid reactive substances) values, and VBN (volatile basic nitrogen). Mold and coliform bacteria were not detected in the samples irradiated at 5 kGy or more. Yeasts and total aerobic bacteria were not detected in the samples irradiated at 10 kGy or more (<$10^2$ CFU/g). Moisture, ash, crude protein, crude fat, carbohydrate, reducing sugar and the contents of volatile basic nitrogen in the irradiated pollen did not show any significant changes by irradiation. Hunter color values, $L^*$, $a^*$ and $b^*$ values were decreased with increment of irradiation dose. TBARS values were increased with an increment of irradiation dose. In conclusion, gamma irradiation at 5 kGy was considered to be an effective treatment to control for mycotoxin producing fungi in rape pollen to minimize changes of general composition and physicochemical properties. Further studies should be investigated to reduce the detrimental effects induced by irradiation.

• Korean journal of food and cookery science
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• v.15 no.6
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• pp.618-625
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• 1999

This study was conducted to investigate the effect of fresh ginseng on the physicochemical, microbiological and sensory properties of Seukbakjee during 45 days of fermentation. Seukbakjee with various levels(0, 2, 4, 6%) of fresh ginseng were fermented at $4^{\circ}$. During fermentation, the pH values were lowered in all Seukbakjee samples, however, those with fresh ginseng were a little higher than control Seukbakjee. Acidity increased continuously during the entire fermentation, in which those of added fresh ginseng increased less than control. As the concentration of fresh ginseng increased, the pH of Seukbakjee were increased. Saltiness was maintained at 1.37~2.62% levels during the whole fermentation. The degree of degradation of reducing sugar and free sugar was much delayed in Seukbakjee added with fresh ginseng. Total vitamin C content of Seukbakjee with fresh ginseng was higher than that of Seukbakjee without fresh ginseng. The number of total bacteria and lactic acid bacteria in Seukbakjee with fresh ginseng was higher than control during the entire fermentation period. In sensory evalution, Seukbakjee with 4% fresh ginseng was the best for taste and flavor. Seukbakjee with 2% fresh ginseng was the best for texture and overall acceptability. Above results suggest that the addition of fresh ginseng improves the quality of Seukbakjee.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.5
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• pp.477-490
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• 2018

This study investigated the changes in the quality of doenjang (a fermented bean paste) with the addition of Sea tangle Saccharina japonica powder fermented by lactic acid bacteria (FSP). Doenjang was prepared without or with FSP and with various amounts of doenjang (0, 0.25, 0.5, 1 and 3% by volume), and fermented at $25^{\circ}C$ for 12 weeks. After 12 weeks, the antioxidant activity, microbiological characteristics, and physicochemical parameters were examined. We detected no significant differences in the color profiles. However, following the addition of FSP to doenjang, the amino nitrogen content and antioxidant properties were enhanced. Furthermore, the FSP-doenjang contained higher levels of ${\gamma}$-aminobutyric acid (297.55-300.03 mg/100 g), a biofunctional ingredient. These results suggest the potential for developing a traditional Korean fermented food with enhanced antioxidant activity and ${\gamma}$-aminobutyric acid content using FSP.

• Food Science and Preservation
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• v.16 no.2
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• pp.217-222
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• 2009

The objective of this study was to obtain basic data on Korean traditional meju collected in 17 regions of Korea, to define and control meju quality. The moisture, crude fat, crude protein, and amino nitrogen contents of meju were 9.83-36.24%(w/w), 17.46-28.74%(w/w), 42.00-45.54%(w/w), and 223.65-1137.68 mg%, respectively. Meju was the enzyme source which made the soy sauce and doenjang. The $\alpha$-amylase, $\beta$-amylase, and protease levels were 130.32-1254.45, 30.07-167.88 and 72.53-340.04 units, respectively. Regional enzyme activities differed widely. Bacterial levels were $4.8{\times}10^7-2.6{\times}10^{10}cfu/g$, and molds and yeasts were at $4.3{\times}10^4-7.9{\times}10^6cfu/g$.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.307-313
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• 1991

A yellow-green, fluorescent siderophore A3 was extracellularly produced under iron-limited growth conditions from Pseudomonas synxantha A3. The physicochemical and biological properties of siderophore A3 were examined. The approxiamte molecular weights of the Fe(III)-siderophore A3-1 complex and Fe(III)-siderophore A3-2 complex were estimated to be about 1,300 and 1,100, respectively, by Bio-gel P2 gel exclusion chromatography. The molar ratio between the siderophore and the Fe(III)was 1.08 mole. The molecular weight of the complex could be calculated with this ratio and the new values were 1,150 and 960, respectively. The binding constant(K) between thesiderophore A3 and Fe(III) that determined by displacing the iron from the Fe(III)-siderophore complex with EDTA was 4.12*10$^{18}$ at pH 5.0. Siderophore A3 appeared to have antibacterial activity on several bacterial strains, however, ferric siderophore Ae complex did not show that activity. The cytotoxicity of siderophore A3 was obtained from Human Chronic Myelogenous Leudemia K562 cells. Inhibition concentration (50%)($IC_{50}$ ) was $0.17\mu$\{g/ml}.