• Journal of Food Hygiene and Safety
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• v.32 no.4
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• pp.249-253
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• 2017

This study aimed to compare the automated most-probable-number (MPN) TEMPO BC and the quantitative mannitol-egg yolk-polymyxin (MYP) plate methods for enumeration of Bacillus cereus in food samples known to be frequently contaminated. Food products that were naturally or artificially contaminated with B. cereus were analyzed by both methods. A difference of less than 1 log (CFU/g) between the two methods was noted in 95.3% samples. There were no significant differences in artificially contaminated products between the two methods in terms of $R^2$ values for sauce products, jorim products, fish products, etc. However, a significant difference was noted for sunsik, fermented soybean products, and products. The linear equation of naturally versus artificially contaminated food was $log_{(TEMPO\;BC)}=0.8453{\times}log_{(MYP\;plate\;agar)}+0.1642$. Statistical analysis of the results showed good agreement between the two methods. Due to growing interest in food safety, the use of the TEMPO BC method may increase. In response to this trend, the results from this study will offer valuable comparative data on the feasibility of existing methods and help develop new approaches for food safety testing.

• Journal of Life Science
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• v.14 no.4
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• pp.664-669
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• 2004

The contamination of Bacillus cereus was investigated in 240 RTE (ready-to-eat) food samples including 118 seafoods, 82 Korean packaged meals and 40 other RTE foods. Many B. cereus presumptive strains were isolated from the enrichment culture in Tryptic Soy Broth (TSB) added polymyxin, followed by selective culture in Mannitol Egg Yolk Polymyxin (MYP) agar and Gram staining. A total of 36 strains (16 in seafoods, 17 in Korean pack-aged meals and 3 in other RTE foods) were identified as B. cereus by the analysis of 61 biochemical tests of the API 50CHB/20E system test and supplementary tests of $\beta$-hemolysis, rhizoid growth, motility and oxidase activity. The 28 strains out of 36 B. cereus isolates produced diarrhoeal enter-otoxin in Brain Heart Infusion (BHI) broth. All isolates were resistant to ampicillin and penicillin antibiotics, and most of them were susceptible to gentamicin, vancomycin, bacitracin, chloram-phenicol, kanamycin and streptomycin. The growth of B. cereus was affected by environmental temperature and incubation time. Culture with temperature under 1$0^{\circ}C$ effectively restricted the growth of B. cereus.

• Korean Journal of Food Science and Technology
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• v.44 no.2
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• pp.155-161
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• 2012

The goal of this study was to investigate the chemical and microbiological characteristics of kimchi products distributed in Japan (5 brands, J-products) and Korea (2 brands, K-products). When their average analyses were compared, J-products showed higher values in pH, total sugar and acetic acid contents, while K-products showed higher values in number of lactic acid bacteria, sugar alcohol and lactic acid contents including textural hardness or chewiness. In addition, the analysis showed great variation in composition levels regarding pH, total sugar and acetic acid contents of J-products, and this fact revealed that different manufacturing processes are being attempted in Japan. Interestingly, some J-products had high concentrations of acetic acid with little mannitol, as this result implies that some manufacturers in Japan produce kimchi by adding acetic acid or lactic acid to control the rate of lactic acid fermentation. The result of this study elucidates the Japanese consumer's taste preference as well as the manufacturing processes in Japanese companies.

• Journal of Embryo Transfer
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• v.13 no.1
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• pp.11-19
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• 1998

This study was to determine the effect of ionomycin and 6-dimethylaminopurine (6-DMAP) and/or elcetrical stimulation on the oocyte activation and production of rabbit nuclear transplant embryos. The oocytes were collected from the oviduct of superovulated rabbits at 14 h post hCG injection and cultured in TCM-199 containing 10% FBS until 19 h post hCG injection. To determine the optimum concentration and exposure time of 6-DMAP, some oocytes were activated with 5 $\mu$M ionomycin for 5 min and then in 2.0 mM 6-DMAP for 0.5 to 3.0 h, or in 1.0 to 3.0 mM 6-DMAP for 2.0 h. Other control oocytes were stimulated electrically(3X, 1.25 kV/cm, 60 $\mu$sec) in 0.3 M mannitol solution supplemented with 100 $\mu$M CaCl$_2$ and MgCl$_2$. The nuclear donor embryos of 8-cell stage were synchronized to G$_1$ phase of 16-cell stage, and the recipient cytoplasms were obtained from removal of the first polar body and a portion of membrane bound cytoplasm of the oocytes collected at 15 h post hCG injection. A separated blastomere was injected into the perivitelline space of the enucleated oocytes. The oocytes injected with nucleus were cultured until 19 h post hCG and then electrofused and activated by electrical stimulation with or without ionomycin and 6-DMAP. These nuclear transplant embryos were cultured in TCM-199 containing 10% FBS in 39˚C, 5% CO2 incubator for 120 h. For the oncytes activated parthenogenetically with electrical stimulation with or with-out ionomycin and the various concentration of exposure time of 6-DMAP, the highest cleavage(92.3%) and development to blastocyst stage(41.0%) were resulted from the oocytes activated by ionomycin and 2.0 mM 6-DMAP for 2.0 h, which were found to be significantly(P<0.05) higher than the cleavage(45.2%) and developement to blastocyst stage(14.3%) from the oocytes activated with electrical stimulation. The significantly(P<0.05) more oocytes(71.4%) developed to 4 cell stage at 24 h post activation by ionomycin and 6-DMAP than those by electrical stimulation(18.9%). For the nuclear transplant embryos, the cleavage rate was similarly high in oocyte activation by electrical stimulation with(79.4%) or without ionomycin and 6-DMAP(70.5%). However, the embryo development to blastocyst stage was significantly(P<0.05) higher in oocyte activation by electrical stimulation with ionomycin and 6-DMAP(44.4%) than by electrical stimulation only(25.0%). The significantly(P<0.05) more nuclear transplant embryos(45.6%) developed to 4 cell stage at 18 h post activation by electrical stimulation with ionomycin and 6-DMAP than those by electrical stimulation only(10.6%). These results indicated that the supplemental oocyte activation by ionomycin and 6-DMAP with electrical stimulation enhanced and accelerated the preimplanted in vitro development of the rabbit nuclear transplant embryos.

• Food Science and Preservation
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• v.23 no.1
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• pp.139-143
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• 2016

This study investigated the effect of electron beam (EB) treatment on the microbial reduction of dried laver (Porphyra tenera) and identified EB-resistant bacteria from the treated dried laver. After EB treatments of 4 kGy and 7 kGy, the numbers of total bacteria and EB-resistant bacteria were measured using tryptic soy agar and mannitol salt agar, respectively. The morphological and biochemical characteristics of each isolated EB-resistant bacteria were investigated and these bacteria were identified. Compared to the control ($1.5{\pm}0.2){\times}10^6CFU/g$, the total bacterial number was significantly decreased to ($5.4{\pm}0.5){\times}10^4CFU/g$ and ($1.1{\pm}0.6){\times}10^4CFU/g$ after EB treatments of 4 kGy and 7 kGy, respectively. With a higher EB dosage, the number of red colonies was almost same, whereas the number of yellow colonies was significantly decreased to ($3.3{\pm}1.2){\times}10^3CFU/g$ and 0 CFU/g for 4 kGy and 7 kGy, respectively. All red and yellow colonies were gram-positive cocci, catalase-positive, and resistant to 3% and 5% NaCl media. From the 16S rDNA sequence analysis, yellow and red colonies were identified as either Micrococcus flavus or M. luteus, with 99% similarity for the yellow colonies, and Deinococcus proteolyticus and D. piscis, with 99% and 97% similarity for the red colonies, respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.14-14
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• 2010

Vitamin C (ascorbic acid) is an essential component for collagen biosynthesis and also for the proper functioning of the cardiovascular system in humans. Unlike most of the animals, humans lack the ability to synthesize ascorbic acid on their own due to a mutation in the gene encoding the last enzyme of ascorbate biosynthesis. As a result, vitamin C must be obtained from dietary sources like plants. In this study, we have developed two different kinds of transgenic potato plants (Solanumtuberosum L. cv. Taedong Valley) overexpressing strawberry GalUR and mouse GLoase gene under the control of CaMV 35S promoter with increased ascorbic acid levels. Integration of the these genes in the plant genome was confirmed by PCR and Southern blotting. Ascorbic acid(AsA) levels in transgenic tubers were determined by high-performance liquid chromatography(HPLC). The over-expression of these genes resulted in 2-4 folds increase in AsA intransgenic potato and the levels of AsA were positively correlated with increased geneactivity. The transgenic lines with enhanced vitamin C content showed enhanced tolerance to abiotic stresses induced by methyl viologen(MV), NaCl or mannitol as compared to untransformed control plants. The leaf disc senescence assay showed better tolerance in transgenic lines by retaining higher chlorophyll as compared to the untransformed control plants. Present study demonstrated that the over-expression of these gene enhanced the level of AsA in potato tubers and these transgenics performed better under different abiotic stresses as compared to untransformed control. We have also investigated the mechanism of the abiotic stress tolerance upon enhancing the level of the ascorbate in transgenic potato. The transgenic potato plants overexpressing GalUR gene with enhanced accumulation of ascorbate were investigated to analyze the antioxidants activity of enzymes involved in the ascorbate-glutathione cycle and their tolerance mechanism against different abiotic stresses under invitro conditions. Transformed potato tubers subjected to various abiotic stresses induced by methyl viologen, sodium chloride and zinc chloride showed significant increase in the activities of superoxide dismutase(SOD, EC 1.15.1.1), catalase, enzymes of ascorbate-glutathione cycle enzymes such as ascorbate peroxidase(APX, EC 1.11.1.11), dehydroascorbate reductase(DHAR, EC 1.8.5.1), and glutathione reductase(GR, EC 1.8.1.7) as well as the levels of ascorbate, GSH and proline when compared to the untransformed tubers. The increased enzyme activities correlated with their mRNA transcript accumulation in the stressed transgenic tubers. Pronounced differences in redox status were also observed in stressed transgenic potato tubers that showed more tolerance to abiotic stresses when compared to untransformed tubers. From the present study, it is evident that improved to lerance against abiotic stresses in transgenic tubers is due to the increased activity of enzymes involved in the antioxidant system together with enhanced ascorbate accumulated in transformed tubers when compared to untransformed tubers. At moment we also investigating the role of enhanced reduced glutathione level for the maintenance of the methylglyoxal level as it is evident that methylglyoxal is a potent cytotoxic compound produced under the abiotic stress and the maintenance of the methylglyoxal level is important to survive the plant under stress conditions.

• Journal of the Korean institute of surface engineering
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• v.3 no.1
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• pp.7-12
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• 1970

Only mannitol or glycerine is generally used for the determination of boric acid in a nickel plating solution in order to make its acidic property so strong that it can be titrated with NaOH. However, these solutions give very amgiguous color change of indicator due to the precipitation of nickel salts . Therefore, only experienced dchemistsorwell trained workimen can accurately confirm the actual end point of the titratiion. For eliminating such interference of nickel salts and easily confirming the end point by any persons , the author attempted to find out a solution which produces no precipitates during the titration in these experiments, and also he tried to funish the reason for ambiguousness in titration. The following results were obtained after many experiments. (1) In any titrations which produce nickel salts such nI(oh)$_2$, the salt is formed umption very approximate to the end point, which shows some error by the consumption of titrant(NaOH) . Then, the pink color of phenolphthalein is absorbed by Ni(OH)$_2$ and the pH jumping at the end pint is also diminished to as little as less than 15% of the total phenophthalein ph range. (2) Known methods by complex salts of citrate,w hich do not produce precipitates of Ni(OH)$_2$, are also not very satisfactory, because, the pH jumping at the end point is only about 35% and the color change of phenolphthalein is form blue-green to purple-blue. (3) New method by complex salts of oxalate were attempted in these experiments. They also did not produce precipitates of Ni(OH)$_2$ and were very satisfactory in color change at the end of point was about 65% and the color change was from blue-green to purpled. In this methods, analytica cost was minimized by the use of less amounts of cheaper chemicals than the conventional citrates complex methods. The mixture of chemicals used was composed methods. The mixture of chemical used was composed of 37g/ι of sodium oxalate(Na$_2$C$_2$O$_4$$.$5H$_2$O), 2g/ι of phenolphthalein, and 400ml /ι of glycerin. The accuracy of analysis was within the error of 0.5%. (4) The procedure of analysis was as follows. One ml of nickel plating solution was taken out and to it were added 20ml of water and 20 ml of the above mixture for the indicator. The solution was titrated with 0.1N NaOH. The quantity of boric acid was calculated by the following equation. Boric acid (g/ι) = 6.184${\times}$F${\times}$ml .

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.196-203
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• 2002

Effect of different levels (0 ,0.05, 0.15, 0.25%) of xanthan gum on kakdugi fermentation was investigated by analyzing physicochemical and sensory characteristics during fermentation at 2$0^{\circ}C$. During fermentation, pH was maintained higher, and total acidity and number of lactic acid bacteria, maintained lower in xanthan gum groups, especially in 0.05% addition group than control. Free sugar amount were higher in xanthan gun groups than control, and glucose and fructose which were the major free sugars, decreased rapidly during fermentation, whereas mannitol increased in all samples, especially in xanthan gum groups. Liquid content of kakdugi was smaller in 0.05% xanthan gum group than control. Viscosity of kakdugi liquid decreased rapidly whereas initial viscosity was maintained in xanthan gum groups. Hardness decreased during fermentation, but at the 7th day of fermentation was higher in 0.05% xanthan gum group than control. The result of sensory evaluation shows that there were no significant difference in sour odor, moldy, sour taste and savory taste among samples. Starch taste was higher in 0.15% or 0.25% xanthan gum, but there is no difference in 0.05% group, compared to control. Overall preference until the 5th day of fermentation, xanthan gum group was not significantly different from that of control but at the 7th day of fermentation, 0.05% addition group was significantly higher than control.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.1
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• pp.41-48
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• 2000

A bacterial strain, designated as JK-43, producing extracellular cyclodextrin glucanotransferase (CGTase)[EC 2.4.1.19] was isolated from kimchi. The CGTase from isolated strain JK-43 showed the transglucosylation activity from soluble starch to L-ascorbic acid(AA) compared to those obtained from other strains. A main product formed by this reaction was identified as $2-O-{\alpha}-glucopyranosyl$ L-ascorbic acid(AA-2G) by testing its susceptibility to ${\alpha}-glucosidase$ hydrolysis, the HPLC profiles, and through the elementary analysis. the ${\beta}-CD,\;{\gamma}-CD$, potato starch and corn starch were identified to be suitable glucosyl donor for transglucosylation reaction on AA by CGTase. Acceptor specificity on AA-2G production was examined by use of AA, Iso-AA and AA-2P. Transglucosylation was observed toward AA-2P as well as AA and Iso-AA. The microorganism isolated from kimchi was identified as a strain of Bacillus sp. JK-43 based on the morphological, cultural, biochemical characteristics and partial 16SrDNA sequence analysis. The maximal CGTase production was observed in a medium containing 1.0% soluble starch, 1.0% yeast extract, 1.0% $Na_2CO_3\;0.1%\;K_2HPO_4,\;and\;0.02%\;MgSO_4{\cdot}7H_2O$ with initial pH 7.0. The strain was cultured at $37^{\circ}C$ for 26 hrs with reciprocal shaking.

• Journal of Mushroom
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• v.9 no.3
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• pp.123-131
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• 2011

Winter mushroom was monitored to investigate the influence of storage temperature on its quality during the storage and distribution phase. In measuring its quality, the contents of saccharides were quantified with its fruiting bodies using HPLC. Although it has been known to be difficult to separate saccharide isomers, our results indicated that Grace Prevail carbohydrate ES $5{\mu}column$ was the best in the separation to analyze the saccharide out of six columns used in this study. In our results, xylose was the main component of saccharide in the fruiting body of winter mushroom(White line mushroom:47.68mg/g, brown line mushroom: 63.28mg/g). In long-term storage, the total amount of saccharide tended to increase, but trehalose content of the disaccharide decreased. In comparison with the paramount amount of lactose and myo-inositol contents in long-term storage at $4^{\circ}C$, lactose wasn't detected when stored at $-1^{\circ}C$.