• Food Science of Animal Resources
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• v.23 no.3
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• pp.262-268
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• 2003

Kefir is a traditional fermented milk in Caucasusian area and is made mainly of milk fermented with lactic acid bacteria and yeasts. Six typical kefir grains were selected from ten kefir grains collected from different locals in Korea. Kefir grains were gelatinous in texture and had various shapes of villi, grapes, leaves, hulled millets, and towels. To investigate predominant microflora of kefir grains, SPC, MRS, M17, Rogosa, and APT agar media were used for viable cell count MRS, SPC, and Rogosa media were most acceptable for bacterial cell counts of the selected kefir grains. From one or two of the SPC agar plates which contained around 25∼50 colonies, all grown colonies were isolated and identified. Most predominant bacteria was identified as Lactobacillus fermentum by API 50 CHL kit. The proportions of Lb. fermentum and Lb. brevis among the total identified bacteria were around 41~88% and M4%, respectively. To select the best preservation method for kefir grains, refrigeration, freezing, and freeze drying were compared. Freeze drying was found most suitable for the preservation of kefir grains, based upon their acid-producing activities and production of off-flavors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.5
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• pp.581-585
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• 2005

Five lactic acid bacteria (LAB) including 2 Lactobacillus strains isolated from Kimchi were evaluated to determine the binding ability to Caco-2 cells and $AFB_1$. LAB were divided into three different groups ; viable, heat-treated, and acid-treated cells. In the radioactive-labeling assay for bound cell counting, viable Lactobacillus Plantarum KCTC 3099 showed the higher adhesion to Caco-2 cells with the binding capacity of $39.2\%$, which was $149\%$ higher than Lactobacillus rhamnosus GG as a positive control. Leuconostoc mesenteroids KCTC 3100 showed the similar binding ability to L. rhamnosus GG. After 1 hour incubation at $37^{\circ}C$ with $AFB_1$, viable L. Planterum KTCC 3099 removed the toxin by $49.8\%$, which was similar level to L. rhamnosus GG. Both heat- and acid-treated groups showed high binding effect but acid-treated group was more effective for both Caco-2 cell binding and $AFB_1$ removal than the other. These results indicate that components of bacterial cell wall might be involved in tile binding to intestinal cells and toxins.

• Korean journal of food and cookery science
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• v.14 no.1
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• pp.1-8
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• 1998

The characteristics of Kimchi, associated with proceeding velocity of fermentation, and microbial changes, were investigated during fermentation where kimchi were prepared by the addition of different kinds of minor ingredients. In all samples, total acidity increased, and the pH and total reducing sugar content decreased as the fermentation proceeded. Redox potentials decreased from early to middle fermentation period but thereafter increased and had the lowest value at optimum ripening stage. The counts of total viable and lactic acid bacteria increased rapidly at the begining and decreased slowly. These bacterial counts of kimchi samples containing ginger, red pepper powder, and mixture of all minor ingredients were higher than those of other samples. The number of Leuconostoc mensenteroides reached the maximum at the optimum fermenting stage, Lactobacillus plantarum appeared at the time when Leu. mesenteroides reduced. All these phenomena were observed earlier in the samples containing raw red pepper and later in the samples added garlic than in other samples. It is suggested that garlic is the ingredient which improved storage capacity by prolonging fermentation period by lactic acid bacteria beneficial to less acidification, and ginger and red pepper powder are materials which gave better taste to kimchi by stimulating the growth of Leu. mesenteroids. And redox potential was an useful indicator in choosing optimum ripening time during fermentation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.556-562
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• 1997

Depletion of nitrite by lactic acid bacteria isolated from Kimchi and the effects of pH and temperature on depletion of nitrite in Lactobacillus MRS broth were investigated. Depletion of nitrite by Lactobacillus plantarum and Lactobacillus sake was low in initial stage of growth but increased during growth at 15 and 2$0^{\circ}C$. L. plantarum and L. sake depleted than 90 and 75% of nitrite(250$\mu\textrm{g}$/$m\ell$) in 1 day of growth at 25 and 3$0^{\circ}C$, respectively, but depleted almost all of nitrite in 2 days. While the effect of Leuconostoc mesenteroides (150$\mu\textrm{g}$/$m\ell$) was lower compared to Lactobacillus(250$\mu\textrm{g}$/$m\ell$). In addition, even high concentrations(600 and 900 $\mu\textrm{g}$/$m\ell$) of nitrite was depleted at 2 days of growth by L. plantarum. pH of growing broth decreased as the increase of growth time and temperature, and depletion of nitrite in- creased as the decrease of pH of growing culture. However, pH of broth related with the decrease of depletion of nitrite at 25 and 3$0^{\circ}C$, but not at 15 and 2$0^{\circ}C$. Therefore, depletion of nitrite was greatly affected by growth temperature rather than by pH.

• Food Science and Preservation
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• v.15 no.3
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• pp.469-476
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• 2008

Lactic acid fermentation of peach juice was carried out by using Lactobacillus plantarum KLAB21, a strain with a high level of antimutagenic activity, When the fermentation was carried out at 25, 30, 37 and $40^{\circ}C$, the highest level in the viable counts and acid production was obtained at $37^{\circ}C$. The sterilized peach juice showed a higher level of viable counts and acid production than the non-sterilized juice. And more viable counts and acid production were observed in the juice fermented by L. plantarum KLAB21 only than that obtained by a mixed culture of L. plantarum KLAB21 and Leuconostoc mesenteroides cells. When the lactic acid fermentation was performed for 5 days, the first 3 days of fermentation resulted in an increase of the viable counts from 8.2 to of 9.2 of log cfu/mL which is the highest level, as well as a decrease of the residual reducing sugar content from 5.6 to 0.1 % Decrease in the viable counts and m significant changes in the residual reducing sugar content were observed for further fermentation up to 5 days. However, the titratable acid content increased and the pH value decreased during the fermentation for 5 days to reach the highest titratable acid content (1,98%) and the lowest pH value (3.14) after 5 days of fermentation. HPLC analysis of the organic acids showed 1,236 mg% of lactic acid and 841 mg% of galacturonic acid contents in the fermented juice which were not detected in the fresh juice before fermentation. Antimutagenic effects of $100\;{\mu}L$ of the fermented peach juice supernatant were shown to be 97.7% against MNNG(N-methyl-N'-nitro-N-nitrosoguanidine), and 58.3% against NPD(4-nitro-O-phenylenediamine) in Salmonella enterica serovar Typhimurium TA100.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.5
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• pp.857-863
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• 2004

The effects of adipic acid on the growth of psychrotrophic kimchi lactic acid bacteria and on the fermentatation of mulkimchi were investigated. Four Leuconostoc and one Lactobacillus species were isolated from kinnchi fermented for 50 days at 6$^{\circ}C$. The growth inhibition rate of adipic acid on psychrotrophic kimchi lactic acid bacteria and control strain, Leuconostoc mesenteroides KCCM l1324, was gradually increased from 0.1% of adipic acid concentration and its growth inhibition rate on selected strains reached 90% at 0.4% addition of adipic acid. On the bases of these results, the Preservative effect of adipic acid on the fermentation of mulkimchi was investigated for 25 days at 1$0^{\circ}C$. The pH of mulkimchi containing adipic acid was lower than that of control mulkimchi at the beginning of fermentation. However, the pH of the control mulkimchi decreased rapidly and the pH is lower at the end of fermentation than that of all samples containing adipic acid. The control increased rapidly during fermentation at the acidity. Adipic acid inhibited the growth of several microorganisms in mulkimchi including Lactobacilli. The number of Lactobacilli in control mutkimchi increased rapidly at the beginning stage of fermentation and it decreased at the end stage due to lowering of pH. However, that of mulkimchi with adipic acid slowly increased. Addition of 0.2% ethyl alcohol showed increase of preservative effect of 0.1% adipic acid in mulkimchi.

• Applied Biological Chemistry
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• v.11
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• pp.1-27
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• 1969

More than thirty kinds of sea food pickles have been eaten in Korea. Out of these salted yellow tail pickle, salted clam pickle, salted oyster pickle, and salted cuttlefish pickle were employed for the analysis of their components, identification of main fermenting microbes, and determination of enzyme characteristics concerned. Also studied was the effect of enzymic action of microbes, which are concerned with the fermenting of pickles, on the production of flavorous 5'-mononucleotides and amino acids. The results are summarized as follows: 1. Microflora observed in the pickles are: (a) Total count of viable cells after 1-2 months of pickling was found to be $10^7$ and that after 6 months decreased to $10^4$. (b) Microbial occurence in the early stage of pickling was observed to be 10-20% Micrococcus spp., 10-20% Brevibacterium spp., 0-30% Sarcina spp., 20-30% Leuconostoc spp., ca 30% Bacillus spp., 0-10% Pseudomonas spp., 0-10% Flavobacterium spp., and 0-20% yeast. (c) Following the early stage of pickling, mainly halophilic bacteria such as Bacillus subtilis, Leuconostoc mesenteroides, Pediococcus halophilus and Sarcina litoralis, were found to exhibit an effect on the fermentation of pickle and their enzyme activities were in direct concern in fermentation of pickles. (d) Among the bacteria participating in the fermentation, Sarcina litoralis 8-14 and 8-16 strains were in need of high nutritional requirement and the former was grown only in the presence of purine, pyrimidine and cystine and the latter purine, pyrimidine and glutamic acid. 2. Enzyme characteristics studied in relation to the raw materials and the concerned microbes isolated are as follows: (a) A small amount of protease was found in the raw materials and 30-60% decrease in protease activity was demonstrated at 7% salt concentration. (b) Protease activity of halophilic bacteria, Bacillus subtilis 7-6, 11-1, 3-6 and 9-4 strains, in the complete media decreased by 10-30% at the 7% salt concentration and that of Sarcina litoralis 8-14 and 8-16 strains decreased by 10-20%. (c) Proteins in the raw materials were found to be hydrolyzed to yield free amino acids by protease in the fermenting microbes. (d) No accumulation of flavorous 5'-mononucleotides was demonstrated because RNA-depolymerase in the raw materials and the pickles tended to decompose RNA into nucleoside and phosphoric acid. (e) The enzyme produced in Bacillus subtilis 3-6 strain isolated from the salted clam pickles, was ascertained to be 5'-phosphodiesterase because of its ability to decompose RNA and thus accumulating 5'-mononucleotide. (f) It was demonstrated that the activity of phosphodiesterase in Bacillus subtilis 3-6 strain was enhanced by some components in the corn steep liquor and salted clam pickle. The enzyme activity was found to decrease by 10-30% and 40-60% at the salt concentration of 10% and 20%, respectively. 3. Quantitative data for free amino acids in the pickles are as follows: (a) Amounts of acidic amino acids such as glutamic and aspartic acids in salted clam pickle, were observed to be 2-10 times other pickles and it is considered that the abundance in these amino acids may contribute significantly to the specific flavor of this food. (b) Large amounts of basic amino acids such as arginine and histidine were found to occur in salted yellow tail pickle. (c) It is much interesting that in the salted cuttlefish pickle the contents of sulfur-containing amino acids were exceedingly high compared with those of others: cystine was found to be 17-130 times and methionine, 7-19 times. (d) In the salted oyster pickle a high content of some essential amino acids such as lysine, threonine, isoleucine and leucine, was demonstrated and a specific flavor of the pickle was ascribed to the sweet amino acids. Contents of alanine and glycine in the salted oyster pickle were 4 and 3-14 times as much as those of the others respectively. 4. Analytical data for 5'-mononucleotides in the pickles are as follows: (a) 5'-Adenylic acid and 3'-adenylic acid were found in large amounts in the salted yellow tail pickle and 5'-inosinic acid in lesser amount. (b) 5'-Adenylic acid, especially 3'-adenylic acid predominated in amount in the salted oyster pickle over that in the other pickles. (c) The salted cuttlefish pickle was found to contain only 5'-adenylic acid and 3'-adenylic acid. It has become evident from the above fact that clam and the invertebrate lack of adenylic deaminase and contain high content of adenylic acid. Thus, they were demonstrated to be the AMP-type. (d) 5'-Inosinic acid was contained in the salted yellow tail pickle in a significant concentration, and it might be considered to be IMP-type. 5. Comparative data for flavor with regard to the flavorous amino acids and the contents of 5'-mononucleotides are: (a) A specific flavor of salted yellow tail pickle was ascribed to the abundance in glutamic acid and aspartic acid, and to the existence of a small amount of flavorous 5'-inosinic acid. The combined effect of these components was belived to exhibit a synergistic action in producing a specific fiavor to the pickle. (b) A specific flavor of salted clam pickle has been demonstrated to be attributable to the richness in glutamic acid and aspartic acid rather than to that of 5'-mononucleotides.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.4
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• pp.602-609
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• 2015

In this study, for modernization of Korean traditional fermented milk, Tarak was made using four kinds of commercial Makgeolli based on the ancient cookbook Suwoonjabbang. Samples of Tarak were periodically collected during 24 h of fermentation at $37^{\circ}C$. After fermentation, changes in pH, titration acidity, and viscosity were analyzed. Fermentation metabolites, including organic acids and free sugars, were analyzed by HPLC. Numbers of yeast and lactic acid bacteria during 24 h of fermentation were measured. The pH of Tarak significantly decreased (P<0.01), whereas its acidity significantly increased (P<0.01) during fermentation. The viscosity increased during 8~24 h of fermentation until curd was separated in Tarak. The level of ethanol increased from 0.37~0.52 mg/mL to 0.51~0.71 mg/mL during 24 h of fermentation. Lactic acid and lactose were the major organic acid and free sugar in Tarak, respectively. The number of lactic acid bacteria increased from 5.23~6.25 log CFU/mL to 9.87~10.41 log CFU/mL at the beginning during 24 h of fermentation. The number of yeast increased from 5.14~6.47 log CFU/mL to 6.99~7.73 at the beginning during 24 h of fermentation at $37^{\circ}C$. The major strains of Tarak were Pediococcus acidilactici, Lactobacillus fermentun, Lactobacillus curvatus, and Saccharomyces cerevisiae. Therefore, we concluded that Tarak was a fermented milk by both lactic acid bacteria and yeast, which was similar to koumiss or kefir.

• Microbiology and Biotechnology Letters
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• v.37 no.4
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• pp.389-398
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• 2009

Development of expression vectors is important for the basic and applied researches on kimchi LAB (lactic acid bacteria). An expression vector, pSJE6c was constructed by inserting P6C promoter sequence from Lactococcus lactis into pSJE, a shuttle vector for E. coli and Leuconostoc species. To test the efficiency of pSJE6c, aga ($\alpha$-galactosidase) and lacZ ($\beta$-galactosidase) genes were expressed in Lactobacillus brevis 2.14. Compared to the pSJE, expression levels of both genes were increased, indicating P6C promoter was better than indigenous promoters. Enzyme activities of L. brevis cells harboring pSJE6caga (pSJE6c with aga) or pSJE6Z (pSJE6c with lacZ) were 1.5-2 fold higher than those with pSJEaga (pSJE with aga) or pSJEZ (pSJE with lacZ). More RNA transcripts were detected in cells harboring pSJE6c based recombinant plasmid. The results indicated that heterologous gene expressions in kimchi LAB could be improved significantly by use of efficient expression vectors.

• Korean Journal of Food Science and Technology
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• v.31 no.3
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• pp.619-624
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• 1999

This work was to study the potential health food use of germinated colored rice after germinating and drying using microwave under vacuum. Colored rice was soaked in water at $15^{\circ}C$ for 2 days and then germinated at $25^{\circ}C$ for $3{\sim}4\;days$. The germinated colored rice was dried by different drying methods: microwave vacuum drying 1, microwave vacuum drying $2\;(drying{\rightarrow}crushing{\rightarrow}drying)$, hot air drying, vacuum drying and freeze drying. Each drier except freeze drier was set to maintain the sample temperature at $60^{\circ}C$. During microwave vacuum drying 1 or 2, the sample reached $60^{\circ}C$ much faster (within 5 min) and was dried much faster ($2{\sim}3\;hrs$ than the other drying methods. The initial drying rate of microwave vacuum drying was ten times faster than that of hot air drying. The microwave vacuum drying 2 retained the highest ${\alpha}-amylase$ activity, followed by microwave vacuum drying 1, freeze drying, vacuum drying, and hot air drying.