• Journal of Food Hygiene and Safety
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• v.19 no.3
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• pp.126-131
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• 2004

This study was conducted to investigate of inhibition activity of yuza (Citrus junos) extracts and juice on nitrite scavenging and N-nitrosodimethylamine (NDMA) formation in model system. Yuza juice was separated into organic acid, ascorbate and phenolic portion using sep-pak $C_{18}$ cartridge, respectively. Nitrite scavenging activity and inhibition of NDMA formation from yuza extract has shown higher inhibition with pH of reaction condition lower and amount of added sample more. And peel extract of yuza was higher than those of flesh extract. Nitrite scavenging activity was excellent juice portion rather that 3 portions. Of the 3 portions, it activity was the highest in the organic acid portion, and decreased in the following order; phenolic acid, ascorbate portion. Therefore, organic acid of yuza was suggested to expect effective ihhibitor of NDMA formation.

• Korean Journal of Food Science and Technology
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• v.41 no.6
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• pp.622-627
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• 2009

The objectives of this study were to evaluate a protease suitable for the enzymatic hydrolysis of a snow crab processing by-product (SPB) and to optimize the hydrolysis conditions using response surface methodology (RSM). The SPB was hydrolyzed at $50^{\circ}C$ and pH 7.0-7.2 to obtain various degree of hydrolysis (DH) using Flavourzyme at an enzyme/substrate (E/S) ratio of 3.0%. The reaction progress curve exhibited an initial fast reaction rate followed by a slowing of the rate. The DH was increased to 30% at 90 min with a final DH 32 to 36%. A central composite experimental design having three independent variables (reaction temperature, reaction time, and E/S ratio) with five levels was used to optimize the enzymatic hydrolysis conditions. Based on the DH data, the optimum reaction conditions for the enzymatic hydrolysis of the SPB were a temperature of $51.8^{\circ}C$, reaction time of 4 hr 45 min, and an E/S ratio of 3.8%. It was demonstrated that the enzymatic hydrolysate of SPB could be used as a flavoring agent or a source of precursors for the production of reaction flavors.

• Journal of the Korean Vacuum Society
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• v.6 no.2
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• pp.114-121
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• 1997

The transparent conductiong thin films of tin oxides were prepared on pyrex glass substrates by the pulse laser deposition. In the atmospheres of vacuum, O2, and $Sn(CH_3)_4$ a polycrystalline $SnO_2$ target was ablated by Nd-YAG laser beam to deposit thin films on the substrates at room temperature, and as-deposited films were subsequently heat-treated in the air for 2 h at 230, 420 and $610^{\circ}C$, respectively. The characteristics of the thin films were examined by UV-VIS-NIR spectrometry and X-ray diffractometry, and the electrical properties were measured by four-point probe method along with film thickness monitored by the stylus method. It was observed that in the presence of $Sn(CH_3)_4$, $SnO_2$ phases were grown even at room temperature. This suggests that the microplasma producted during the laser ablation plays an important role in the dissociaation of precursor molecules.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.832-840
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• 2019

To improve the electrochemical performances of the cathode materials, boron-doped $LiNi_{0.90}Co_{0.05}Ti_{0.05}O_2$ were synthesized by using concentration gradient precursor. The characteristics of the prepared cathode materials were analyzed by XRD, SEM, EDS, PSA, ICP-OES and electrical conductivity measurement. The electrochemical performances were investigated by initial charge/discharge capacity, cycle stability, C-rate, cyclic voltammetry and electrochemical impedance spectroscopy. The cathode material with 0.5 mol% boron exhibited a capacity of 187 mAh/g (0.5 C) in a voltage range of 2.7~4.3 V(vs. $Li/Li^+$), and an capacity retention of 94.7% after 50 cycles. In the relatively high voltage range of 2.7~4.5 V(vs. $Li/Li^+$), it showed a high capacity of 200 mAh/g and capacity retention of 80.5% after 50 cycles.

• Journal of Mushroom
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• v.17 no.1
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• pp.12-18
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• 2019

An auxin-producing bacterium Yangsong-1 was isolated from a button mushroom bed in Chung cheongnam-do. The strain Yangsong-1 was classified as a novel strain of Arthrobacter enclensis based on a chemotaxonomic and phylogenetic analysis. The isolated A. enclensis Yangsong-1 was confirmed to produce indole-3-acetic acid (IAA), which is one of the auxin hormones. When the concentration of IAA was assessed by HPLC quantity analysis, the maximum concentration of IAA, $152.903mg\;L^{-1}$, was detected from the culture broth incubated in R2A medium containing 0.2% L-tryptophan for 48 h at $35^{\circ}C$. A negative relationship between IAA production and pH was estimated to show that the increase in IAA caused pH acidification of the culture. The effect of the supplement on L-tryptophan, a known precursor of IAA production, appeared to be at maximal production at 0.2% concentration and was rather reduced at concentration above 0.4%. To investigate the growth-promoting effects on the crops, the culture broth of A. enclensis Yangsong-1 was placed in water cultures and seed pots of mung beans and lettuce. In consequence, the adventitious root induction and root growth of mung beans and lettuce were 1.5 and 1.9 times higher, respectively, than those of the control.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.426-431
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• 2013

Nanosized $TiO_2$ particles were prepared from titanium (IV) sulfate solution using base solutions at low reaction temperature ($95^{\circ}C$) and atmospheric pressure by hydrothermal precipitation method without calcination. The effects of preparation conditions, such as kind of base solutions (NaOH, $NH_4OH$, Monoethanolamine, Diethanolamine, Triethanolamine) and surfactants (CTAB, Span 20, SDBS), concentration of surfactants, temperature and pH, on the physical properties of $TiO_2$ particles have been investigated by XRD, SEM and Zeta-potential meter. Absorption area was also investigated by DRS in order to confirm the photocatalytic activity of the nanosized $TiO_2$ particles. It was turned out that, among base solutions, NaOH provides the smallest $TiO_2$ particles with excellent crystallinity. And cationic surfactant (CTAB) prepared smaller $TiO_2$ particles than any other surfactants. When CTAB is added in the concentration ratio of $Ti(SO_4)_2$:CTAB=10:1, $TiO_2$ particles with particle diameter of 5.8 nm were prepared. This is approximately 1/10 of that prepared without CTAB.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.37-43
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• 2018

Optimization of the lactic acid fermentation process was carried out to produce an old antler extract fortified with ${\gamma}$-aminobutyric acid (GABA). An old antler extract (OAE; 5%, w/v) obtained using a herbal extractor showed the highest contents of solids (1.75%) and proteins ($980{\mu}g/mL$). It also showed the highest total amino acid contents of $13,659{\mu}g/mL$, with glycine, proline, and glutamine concentrations of 1,945, 3,405, and $1,641{\mu}g/mL$, respectively. For the over-production of GABA, OAE was fermented with Lactobacillus plantarum EJ2014 in the presence of 0.5%, 1.5% glucose, and 3.5% MSG at $30^{\circ}C$ for 7 days. The fermented OAE showed high viable cell count of $2.0{\times}10^8CFU/mL$, pH of 6.56 and 0.77% acidity after 7 days. In particular, the acidity was greatly decreased by fermentation for 3 days, and 1.4% GABA was produced by the efficient conversion of the substrate, mono sodium glutamate.

• Korean Journal of Ichthyology
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• v.18 no.2
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• pp.65-77
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• 2006

Gene transcripts potentially responsive to the heat stress were surveyed by cDNA microarray analysis in mud loach (Misgurnus mizolepis). Transcriptional profiles of hepatic tissue in the fish exposed to either $23^{\circ}C$ or $32^{\circ}C$ for 4 weeks were compared each other by 3 replicated hybridization assays using 1,124 unigene clones selected from mud loach liver expressed sequence tags (ESTs). A total of 93 clones showed the substantially increased mRNA levels (>2-fold) in $32^{\circ}C$-exposed group when compared in $23^{\circ}C$control group. It includes various enzymes and proteins involved in energy pathway, protease/protein metabolisms, immune/antioxidant functions, cytoskeleton/cell structure, transport and/or signal transduction. Maximum level of increase was up to 15-fold relative to $23^{\circ}C$ treatment. Heat exposure also resulted in the significant decrease (less than 50% relative to $23^{\circ}C$-exposed fish) of the transcriptional activities in 85 genes. Besides the above categories, yolk protein (vitellogenin) and ribosomal proteins were notably down regulated in the fish exposed to heat stress. A number of novel gene transcripts were also detected in both up-regulated and down-regulated groups.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.120-126
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• 1989

Streptococcus diacetylactis and Leuconostoc cremoris were isolated from commercial culture and the effects of culture conditions on the diacetyl production by these strains and their mixture(1:1) were investigated. Optimum temperatures and culture times for the diacetyl production by Str. diacetylactis, Leu, cremoris and their mixture were 60hr at $22^{\circ}C$(diacetyl content, 2.24ppm), 48hr at $22^{\circ}C$(2.29ppm) and 48hr at $22^{\circ}C$ (2.21ppm), respectively Optimum initial pH for the diacetyl production by Str. diacetylactis, Leu. cremoris and the mixture were all 4.8(4.32, 6.66, 7.30ppm, respectively) and optimum sodium citrate concentrations(%, w/v) were 0.30(2.58ppm), 0.1(2.54ppm) and 0.1(2.52ppm), respectively. The diacetyl contents were gradually increased according as inoculation rates(%, w/v) were increased. The amounts of diacetyl produced under optimum conditions at 24hr incubation by Str. diacetylactis, Leu. cremoris and the mixture were 4.40, 6.59 and 7.25ppm, respectively. The most effective factor affecting diacetyl production under optimum condition was pH.

• Microbiology and Biotechnology Letters
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• v.26 no.6
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• pp.537-544
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• 1998

The cultivation conditions of transformant Alcaligenes eutrophus AER5 harboring cloned phbC gene for mass production of poly (3-hydroxybutyrate-3-hydroxyvalerate)[P(3HB-3HV)] containing high molar fraction of 3-hydroxyvalerate (3-HV) were investigated. In two-stage batch cultivation, transformant accumulated P(3HB-3HV) containing 52.2 mol% of 3HV compared to 30 mol% of parent strain A. eutrophus H16. The increased 3-HV molar fraction was due to the amplified activity of PHB synthase participating in condensation of 3-HB and 3-HV. To increase efficiency of P(3HB-3HV) accumulation, fructose was added along with precursor compound valerate, and total cell mass and P(3HB-3HV) concentrations remarkably increased, but not 3-HV molar fraction. The effect of magnesium ion showed that P(3HB-3HV) concentration and 3-HV molar fraction were significantly increased upto 6.1 g/L and 71.3 mol% at 0.01 g/L of MgSO$_4$, respectively. The efficiency of several pH adjuster, NaOH, NaOH and (NH$_4$)$_2$SO$_4$, and NH$_4$OH, on total cell mass, p(3HB-3HV) concentration, and 3-HV molar fraction was also compared. To overcome the disadvantage of two-stage cultivation, one-stage intermittent fed-batch cultivation was attempted, such a way 10.0 g/L of fructose was supplied for cell growth at initial 36 hr and then 10.0 g/L of valerate and 5.0 g/L of fructose were applied to induce the accumulation of P(3HB-3HV), consequently, 10.4 g/L of P(3HB-3HV) with 38 mol% of 3-HV fraction could be obtained after 72 hr. These results can be used for elucidating cultivation strategy for mass production of P(3HB-3HV) containing high 3-HV molar fraction using transformant A. eutrophus AER5 harboring cloned phbC gene.