• Korean Journal of Food Science and Technology
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• v.43 no.3
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• pp.277-281
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• 2011

A rapid and very sensitive high-performance liquid chromatography/atmospheric-pressure chemical-ionization mass spectrometry method to detect ethylenethiourea (ETU) fungicide residues in fruits was developed. Methylene chloride was used as the surface extraction solvent for the target component. Recovery rates improved when cysteine hydrochloride and sodium carbonate were added to product prior to fortification. The limits of detection and quantification were approximately 0.006 and 0.02 mg/kg, respectively, from mandarin oranges. Recoveries from mandarin oranges, oranges, bananas, and pears, spiked in the range of 0.05-0.5 mg/kg, averaged 80-100%. The proposed method was used to monitor the presence of ETU in commercial fruits purchased from different markets in Seoul, Korea. ETU was found in four orange peels and in three mandarin orange peel samples. The highest ETU residue levels were $73.6{\mu}g/kg$ and $29.8{\mu}g/kg$.

• Korean Journal of Food Science and Technology
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• v.40 no.1
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• pp.21-30
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• 2008

In this study, the antioxidant activities of 27 medicinal herbs and plants were measured. The dried medicinal herbs and plants were pulverized and extracted by water, 15% ethanol, and 45% ethanol, respectively at above $80^{circ}C$ for 90 minutes. The original and diluted extracts were tested for their antioxidant activities by 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical-scavenging activity assay. Cornus officinalis (C) and Scutellaria baicalensis (S) were selected to develop rice wines with higher antioxidant activities, based on the result of the 45% ethanol extraction. The rice wine developed using sample showed the highest antioxidant activity as comparing to those of other commercial rice wines. The rice wine samples were analyzed for titratable acidity, pH, $^{\circ}Brix$, reducing sugar content, color (L, a, b), amino-acidity, and ultraviolet absorption. The preferences for color, aroma, and overall acceptability were determined using a 9-point hedonic scale by 150 consumers. The sweetness, sourness, fruitiness, color, and medicinal herb-taste levels of the developed rice wines were also evaluated, using a 9-point just-about-right scale. The mean overall acceptability score of c (5.54) was higher than that of sample S. Based on the results, the sourness and medicinal herb-taste levels of sample s should be modified to higher levels, and the fruitiness of sample S also needs to be adjusted. For a future study, the final compositions of the developed rice wines will be adjusted for product launching based on the preference test data acquired in this study.

• The Korean Journal of Pharmacology
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• v.32 no.2
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• pp.127-138
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• 1996

The effects of adenosine analogues on the electrically-evoked acetylcholine(ACh) release and the influence of ischemia on the effects were studied in the rat hippocampus. Slices from the rat hippocampus were equilibrated with $0.1{\mu}M$ $[^3H]-choline$ and the release of the labelled product, $[^3H]-ACh$, was evoked by electrical stimulation(3 Hz, 2 ms, 5 $VCm^{-1}$ and rectangular pulses for 2 min), and the influence of various agents on the evoked tritiumoutflow was investigated. Ischemia(10 min with 95% $N_2$ + 5% $CO_2$) increased both the basal and evoked ACh release. These increases were abolished by glucose addition into the superfused medium, and they significantly inhibited either by 0.1 & $0.3{\mu}M$ TTX pretreatment or by removing $Ca^{++}$ in the medium. MK-801($1{\sim}10{\mu}M$), a specific NMDA receptor antagonist, and glibenclamide $(1{\mu}M)$, a $K^+-channel$ inhibitor, did not alter the evoked ACh release and nor did they affect the ischemia-induced increases In ACh release. However, polymyxin B(0.03 mg), a specific protein kinase C inhibitor, significantly inhibited the effects of ischemia on the evoked ACh release. Adenosine and $N^6-cyclopentyladenosine$ decreased the ACh release in a dose dependent manner in ischemic condition, though the magnitude of inhibition was far less than those in normal(normoxic) condition. However, the treatment with $5{\mu}M$ DPCPX, a potent $A_1-adenosine$ receptor antagonist, potentiated the ischemia-effect. These results indicate that the evoked-ACh release is potentiated by ischemia, and this process being most probably mediated by protein kinase C, and that the decreased effect of ACh release mediated by $A_1-adenosine$ receptor is significantly inhibited in ischemic state.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.82-89
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• 1998

This study was performed to elucidate the purification and characterization of pretease from saewoo-jeot, a Korean traditional salt-fermented shrimp product. The protease in saewoo-jeot (Acetes japonicus) were extracted, desalted through electrodialysis and purified by ammonium sulfate fractionation, Sephadex G-100 gel filtration and DEAE-cellulose column chromatography. Purified enzyme had specific activity of 8.4 unit/mg, yield of 14% and purification fold of 9.8. Purified enzyme was confirmed as single band protein by polyacrylamide gel electrophresis and the molecular weight was estimated to be about 24 kDa. The optimal pH and temperature for the enzyme activity were 8.0 and $40^{\circ}C$, respectively. The range of its stability to the pH and temperature were 7.0 to 10.0 and $30^{\circ}C\;to\;60^{\circ}C$, respectively. The activity of enzyme to synthetic substrate showed BAPNA and TAME. The enzyme was activated significantly by manganese ions, while inhibited by STI, TLCK. metals $(K^+,\;Li^+,\;Na^+,\;Ca^{++},\;Co^{++},\;Cu^{++},\;Mg^{++},\;Ba^{++},\;Hg^{++},\;Zn^{++},\;Fe^{+++})$. The Km value of the enzyme was $5.1{\times}10^{-7}\;M$ to hammersten casein. It's suggested that purified protease from saewoo-jeot seemed to be trypsin-like enzyme.

• Korean Journal of Food Science and Technology
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• v.32 no.3
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• pp.525-530
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• 2000

A study was carried out to establish the detection method of irradiated agricultural products cultivated in Korea by Thermoluminscece(TL). Samples were irradiated using Co-60 gamma rays at various doses(0.05, 0.1, 0.2, 0.3 and 0.5 kGy). After irradiation, separated minerals of the samples measured by TL. TL intensity increased with increasing doses and the irradiated samples were higher than the non-irradiated samples. TL first and second glow curves showed maximum TL temperature point at $176.16{\sim}190.08^{\circ}C$ and $143.84{\sim}146.56^{\circ}C$, respectively. All the irradiated samples can be classified correctly by the shape of the glow curve and the glow curve ratio. Correlation coefficients of ginger, carrot, potato and sweet potato were 0.9968, 0.8522, 0.9612 and 0.9071, respectively, that showed very high correlation between irradiation dose and TL intensity. Therefore, these results suggest that TL measurement is an useful detection method for irradiated agricultural products.

• Korean Journal of Food Science and Technology
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• v.22 no.6
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• pp.611-617
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• 1990

This study was conducted to breed a high vitamin $B_{12}$ producer by the fusion of protoplasts between Bacillus natto and Bacillus megaterium. Auxotrophic mutants of Bacillus natto SH-34 ($thr^-try^-rif^r$) and Bacillus megaterium BK-13 ($arg^-ade^-lys^-str^r$) which showed high protease activity and production of vitamin $B_{12}$, respectively, were isolated for the fusion experiment. Protoplasts were induced by incubating the cells with lysis solution containing $500{\mu}/ml$ lysozyme, and the ratio of protoplast and regeneration formation were ranged from 99% and 67%, respectively. Fusion frequencies of fusants between Bacillus natto SH-34 and Bacillus megaterium BK-13 were appeared in the ranges of $1.0{\times}10^{-5}$ under the treatment of 30% PEG 6000 containing 3% PVP. The fusant, MNF-72 showed the highest product yield of $7.85{\mu}g/g-cell\;vitamin\;B_{12}$ in production medium. For the improvement of productivity, the immobilization of fusants with sodium alginate was carried out. In batch and continuous fermentation systems, the productivity were determined to be $0.58{\mu}g/ml.hr\;and\;0.80{\mu}g/ml.hr\;vitamin\;B_{12}$ under optimum condition, respectivity.

• Korean Journal of Food Science and Technology
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• v.9 no.3
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• pp.183-189
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• 1977

Studies were made of the continuous production of Pyridoxal 5'-phosphate (pyridoxal-p) on simultaneously immobilized cell column. Whole-cell of Pseudomonas polycolor having high activity of pyridoxine 5'-phosphate (pyridoxine-p) oxidase and Kloeckera sp. No. 2201 having high activity of catalase were used as the enzyme materials. The enzyme sources were entrapped in a polyacrylamide gel. Enzymatic properties of the simultaneously immobilized cells were investigated, comparing with those of the mixed whole-cells of the microorganisms. The simultaneously immobilized cells had higher enzyme activity than singly immobilized cells of Pseudomonas polycolor. From this result, the simultaneously immobilized pyridoxine-p oxidase-catalase system could be available to exert a protective effect upon the pyridoxine-p oxidase by destroying $H_2O_2$ which is a by-product of pyridoxine-p oxidation. The optimum pH was 9.0 for the immobilized cells and the whole-cells. The optimum temperature was $45^{\circ}C$ for the immobilized cells and $40^{\circ}C$ for the whole-cells. The pyridoxine-p oxidase of the immobilized cells were activated by $Hg^{++}$ and some SH-compounds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.5
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• pp.361-372
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• 1990

Processing conditions of whole sardine into modified fish sauce were investigated. Thawed and chopped sardine was homogenized and hydrolyzed using commercial proteolytic enzymes such as complex enzyme-2000($2.18{\cdot}10^4U/g solid$) and alcalase($1.94{\cdot}10^4\;U/g solid$) in a cylindrical vessel with 4 baffles and 6-bladed impeller. Optimal pH, enzyme concentration and temperature for the hydrolysis with complex enzyme-2000 were 7.0, $7\%$ (W/W) and $52^{\circ}C$, and-those with alcalase were 8.0, $6\%$ (W/W) and $60^{\circ}C$. In both cases, the reasonable amount of water for homogenization, agitation speed and hydrolyzing time were $100\%$ (W/W), 100 rpm and 210 minutes. Thermal treatment of the filtered hydrolysate at $90^{\circ}C$ for 2 hours with $6\%$ of invert sugar was adequated to inactivation of the enzymes and pasteurization of the hydrolysate. Flavor, taste and color of the hydrolysate were improved during the heating process in which the browning products might participate. The content of free amino nitrogen in the fish sauce seasoned with $15\%$ of table salt was ca. $1,640 mg\%$. Yield of the fish sauce based on the contents of proteinous and free amino nitrogen in the raw whole sardine was ca. $86\%$, and ca. $96\%$ of these compounds of the fish sauce was in the form of free amino nitrogen. The pH, salinity and histamine content of the fish sauce were $6.1\~6.3,\;14.2\~14.3\%$ and less than $10\;mg\%$.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.1
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• pp.15-29
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• 2005

Statement of problem. The adjustable dental impression trays were made for being adjusted their width automatically along the width of dental arch. Purpose. The purpose of this study was to investigate the best retentive form of adjustable dental impression tray, and so to make it a more satisfactory product. Material and methods. The eight pairs of adjustable trays were made of ABS(acrylonitrile butadiene styrene) with different distribution of holes and with or without the rim on the border area of them. The experiment was done with the horse-shoe shaped metal plate to pull out the set impression body from the tray, and the tray jig which was made for holding the tray on a lower part of Universal Testing Machine(UTM, Zwick Z020, Zwick Co., Germany). After the impression in the tray was allowed to set four minutes, a tensile force was applied at right angles to the tray which had been previously seated on the jig. The force was applied to measure a maximum retentive force by use of a UTM at a constant strain rate of 100mm per minute. A 2-factor analysis of variance (p<.05) was used to determine whether differences existed among distribution of retentive holes and between rim existing and not. Results. 1 The retentive force of the upper and lower resin tray with 2mm holes on the tray border was highest(25.83/24.98kg). (p<.05) 2. As the tray had more retentive holes, it was less retentive. 3. There was no significant difference in the retentive force of the varied hole intervals in the case of distributing all the area. (p>.05) 4. The rimless trays were more retentive generally, than the rimmed trays except 2 case: upper tray group-all area / 2 mm, intervals and lower tray group-margin only / 2 mm, intervals.(p<.05) 5. Most of the adjustable trays were showed higher retentive force than perforated metal tray except the lower group that perforated on the all area at intervals of 2 mm.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.752-756
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• 2002

Green-emitting $Zn_2SiO_4:Mn$ phosphors for PDP(Plasma Display Panel) application were synthesized by colloidal seed-assisted spray pyrolysis process. The codoping with $Gd^{3+}/Li^+$, which replaces $Si^{4+}$ site in the willemite structure, was performed to improve the luminous properties of the $Zn_2SiO_4:Mn$ phosphors. The particles prepared by spray pyrolysis process using fumed silica colloidal solution had a spherical shape, small particle size, narrow size distribution, and non-aggregation characteristics. The $Gd^{3+}/Li^+$ codoping amount affected the luminous characteristics of $Zn_2SiO_4:Mn$ phosphors. The codoping with proper amounts of $Gd^{3+}/Li^+$ improved both the photoluminescence efficiency and decay time of $Zn_2SiO_4:Mn$ phosphor particles. In spray pyrolysis, the post-treatment temperature is another factor controlling the luminous performance of $Zn_2SiO_4:Mn$ phosphors. The $Zn_{1.9}SiO_4:Mn_{0.1}$ phosphor particles containing 0.1 mol% $Gd^{3+}/Li^+$ co-dopant had a 5% higher PL intensity than the commercial product and 5.7 ms decay time after post-treatment at $1,145^{\circ}C$.