• Korean Journal of Medicinal Crop Science
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• v.18 no.6
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• pp.389-397
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• 2010

This work was to improve antimicrobial activities of horseradish by encapsulated with edible biopolymers such as lecithin and gelatin since it has been difficult to directly use horseradish extracts into foods and food containers due to its strong and undesirable flavors. It was shown that most of the nanoparticles containing the extracts were well formed in round shape with below 400 nm diameter as well as fairly stable and less odd flavors in various pH ranges by measuring zeta potentials. The encapsulation efficiencies of nanoparticles were estimated as 66.6% and 53.4% for lecithin and gelatin, respectively. Minimal Inhibitory Concentration (MIC) of both nanoparticles against G(+), Listeria monocytogenes and G(-), Salmonella typhimurium were also measured as 79 ppm based on AIT concentrations in the extracts, whose activities were about 65% higher than the case of adding crude extract. It was also found that the nanoparticles efficiently penetrated into the cell membrane and started to destruct the cells after 6 hours cultivation under Transmision Electron Microscopy observation. These results prove that the nano-encapsulation of the horseradish extracts can be employed to directly treat into the foods and food containers for antimicrobial purposes with the aids of aerosolization system, by using small amounts of the extracts and having less flavors due to masking effects of nanoparticles.

• Korean Journal of Materials Research
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• v.8 no.5
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• pp.408-412
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• 1998

Thermoelectric properties of Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$(0.05$\leq$x$\leq$0.25) prepared by mechanical alloying and hot pressing, were investigated. Contrary to the p-type behavior of single crystals, the hot-pressed Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$ exhibited ntype conduction without addition of donor dopant. When $Bi_2(Te_{0.85}Se_{0.15})_3$powders were annealed in (50% $H_2$ + 50% Ar) atmosphere, the hot-pressed specimen exhibited a positive Seebeck coefficient due to the reduction of the electron concentration by removal of the oxide layer on the powder surface and annealing-out of the excess Te vacancies. Among the Bi$_{2}$(Te$_{1-x}$Se$_{ x}$)$_{3}$fabricated by mechanical alloying and hot pressing, $Bi_2(Te_{0.85}Se_{0.15})_3$ exhibited a maximum figure-of-merit of 1.92 $\times$ $lO^{-3}$/K.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.6
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• pp.1014-1019
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• 1994

To develope natural food preservatives, ethanol extract was preapred from the leaf mustard (Brassica juncea Coss) and antimicrobial activities were examined against 12 microorganisms which were food borne pathogens and/or food poisioning microorgaism and food-related bacteria and yeasts. The most active animicrobial concentration of the ethanol extract for most Gram positive microorganisms, Gram negative microorganisms, and lactic bacteria and yeasts was found to be 10, 20 and 40 mg/ml, respectively. when tested by a dose-response manner. Growth of Escherichia coli and STaphylococcus aureus were completely inhibited 4 hours after the addition of more than 20mg/ml of ethanole ethanol extract to the logarithic phase. Scanning electron icrographs of E. coli and Staph, aureus treated with ethanol extrract exhibited morphological changes, including the irregularly contracted cell surface of E. coli and expanded ellipsoidal shape of the Staph. aureus.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.59-75
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• 2016

Reduced or black $TiO_{2-x}$ materials with oxygen-deficiency have been achieved by creating oxygen vacancies and/or defects at the surface using different methods. Fascinatingly, they exhibited an extended absorption in VIS and IR instead of only UV light with bandgap decrease from 3.2 (anatase) to ~1 eV. However, despite the dramatic enhancement of optical absorption in black $TiO_{2-x}$ materials, they have failed to show expected visible light-assisted water splitting efficiency. This was ascribed to the high concentration of the surface defects and/or oxygen vacancies, considered as an electron donor to enhance donor density and improve the charge transportation in black $TiO_2$ can also act as charge recombination centers, which eventually decrease photocatalytic activity. Therefore, a black ot reducd $TiO_2$ material with optimized properties would be highly desired for visible light photocatalysis. In this report, a new controlled magnesiothermic reduction has been developed to synthesize reduced black $TiO_{2-x}$ in the presence $H_2/Ar$ for photocatalytic $H_2$ production from methanol-water system. The material possesses an optimum band gap and band position, oxygen vacancies, and surface defects and shows significantly improved optical absorption in the visible and infrared region. The synergistic effects enable the reduced $TiO_{2-x}$ material to show an excellent hydrogen production ability along with long-term stability under the full solar wavelength range of light and visible light, respectively, in the methanol-water system in the presence of Pt as a co-catalyst. These values are superior to those of previously reported black $TiO_2$ materials. On the basis of all the results, it can be realized that the outstanding activity and stability of the reduced of $TiO_{2-x}$ NPs suggest that a balanced combination of different factors like $Ti^{3+}$, surface defects, oxygen vacancy, and recombination center is achieved along with optimized bandgap and band position during the preparation employing magnesiothermic reduction in the presence of $H_2$. The controlled magnesiothermic reduction in the presence of $H_2$ is one of the best alternative ways to produce active and stable $TiO_2-based$ photocatalyst for $H_2$ production.

• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.23-29
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• 2005

To investigate potential characteristics of clay minerals (illite, kaolin, zeolite, vermiculite, and bentonite) for food industry application, antioxidative properties of clay minerals, electron-donating ability (EDA), peroxide value (POV), and thiobabituric acid (TBA) were measured, and antimicrobial activity against several food spoilage microorganisms were evaluated by minimum inhibition concentration (MIC) method. Changes in components by cooking clay minerals added to stored rice were measured by GC-MS. DPPH (1,1-diphenyl-2-picrylhydrazyl) analysis results revealed bentonite has strongest EDA at 20.6%. Antioxidant activities measured based on POV were similar to DPPH results. Induction period of linoleic acid with vermiculite was longest among. TBA results revealed zeolite hasstrongest antioxidant ability. Growth inhibition against E. coli and S. aureuswas observed in illite, vermiculite, and zeolite. Aroma components indicated decrease in hex anal, pent anal, non anal, linoleate, stearic acid, and oleic acid when clay minerals were added to stored rice. These results indicate that several clay minerals have antioxidative and antimicrobial abilities and improve flavor profiles in stored rice.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.8
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• pp.955-959
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• 2007

This study was carried out to determine the antioxidative and antigenotoxic effects of buckwheat (Fagopyrum esculentum Moench) sprout using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical donating method and micronucleus test. Buckwheat sprout were extracted with 70% ethanol and then further fractionated to n-hexane, chloroform, ethyl acetate (EtOAc), butanol and water. Among the five fractions, the EtOAc fraction showed the highest electron donating activity ($RC_{50}$ 26.1 ${\mu}g/mL$). The effects of buckwheat sprout extracts on the frequencies of micronucleated polychromatic erythrocytes (MNPCEs) induced by MNNG (N-methyl-N'-nitro-N-nitrosoguanidine) were investigated in the bone marrow. 10, 20, 40 and 80 mg/kg of each extract were administered to animals immediately after injection of MNNG and the exposure time was 36 hrs. Inhibition effects of buckwheat sprout ethanol extract were 23.4%, 40.6%, 56.3% and 73.4%, respectively. When the fraction of hexane, chloroform, ethyl acetate, butanol and water from 70% ethanol extract were treated with concentration of 80 mg/kg, the suppression rates of the MNPCE were 64.1, 67.9, 75.8, 74.2 and 63.3%, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.5
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• pp.660-664
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• 2011

We investigated the improvement of the antioxidative activity of black garlic with enzymatic treatment and lactic acid bacteria cultivation conditions. Celluclast, a commercially-available polysaccharide hydrolyase, was selected to obtain high total polyphenol content in a black garlic suspension. A lactic acid bacterial strain showing fast growth and high acid production in a black garlic suspension was isolated from Kimchi. This strain was identified as Lactobacillus pentosus 310-7. Enzymatically hydrolyzed black garlic was fermented using the L. pentosus 310-7 strain at $30^{\circ}C$ for 15 hr. The pH and titratable acidity achieved were 4.24 and 0.35%, respectively, after 15 hr fermentation. The viable cell population of L. pentosus 310-7 slowly increased to 7.54 log CFU/g. The polyphenolic compound content, known antioxidants, in black garlic was enhanced with Celluclast treatment and L. pentosus 310-7 cultivation. Total polyphenolic compounds were increased to approximately 60% of the initial concentration, and electron donating ability was also improved, from 39.8 to 65.9%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.8
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• pp.1111-1117
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• 2009

Effect of Rubus coreanum Miquel and Opuntia ficus-indica var. saboten in combination with chicken breast and wheat gluten on functional properties and physicochemical characteristics during processing of cooked noodles were investigated. These studies were carried out to investigate functional properties of Rubus coreanum Miquel and Opuntia ficus-indica var. saboten by the antioxidant ability. Antioxidant activities were evaluated by electron donating, xanthine oxidase inhibition rate and contents of total polyphenols. Overall, the antioxidant activities of hot water extracts were a little higher than those of ethanol extracts. Also, the antioxidant abilities at the concentration of 1,000 ppm in hot water extracts were higher than those of ethanol extracts by the determination of total polyphenol content and DPPH, which showed 150.25 mg% in extracts of Rubus coreanum Miquel and showed 69.36% in extracts of Opuntia ficus-indica var. saboten. The effects on processing characteristics of cooked noodles were investigated in combination with transglutaminase (TGase), plant extracts, wheat gluten and chicken breast. Cooking time was very short as 340 second in CB (cooked breast), compared to other treatments. In contrast, NCB (non cooked breast) took a longer time as 779 second. Also, CB was higher than NCB, which showed 146.3% in CB and 61.5% in NCB in water absorption ratio during cooking of noodles. Tubidity of soup was the lowest at 0.240 in NCBT (non cooked breast transglutaminase), which means the lowest loss of solid in noodle during cooking. In case of treatment of TGase, overall texture properties were higher than other samples in hardness, cohesivness, springness and gumminess. In sensory evaluations, cooked noodles treated with TGase showed a higher percentage of overall acceptability than other treatments.

• Korean Journal of Microbiology
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• v.24 no.2
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• pp.154-160
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• 1986

In order to develope interspecific fusion of the genus Cellulomonas capable of assimilation cellulose, the optimun conditions for the protoplast formation was investigated to examine the susceptibility of cell wall, between different species of the same genus using scanning electron microscope. The variation in the susceptibilities of Cellulomonas sp. CS 1-1 and C. flavigena to lysozyme treatment were considerably remarkable, although they belong to the same genus. The rate of protoplast formation of CS1-1 was 99.9% being treated with lysozyme $(100{\mu}g/ml)$ for 30 minute and that of C. flavigena was about 80% being treated at the concentration of $600{\mu}g/ml$ of lysozyme for 6 hours. The susceptibility of cell wall to the lysozyme treatment on protoplast formation of the strain, CS1-1 seems not to be depend on the cultural periods of cells. On the contrary, that of C. flavigena was considerably depend on the periods. Cells of C. flavigena at mid exponential phase could be more efficiently converted to protoplast cells than those at late exponential phase be done. The rate of the protoplast formation was 95%, when cells of C. flavigena at mid exponential phase were treated with lysozyme $600{\mu}g/ml$ for 6 hours and observed by SEM. In the evalution of protoplast formation of the CS1-1 results of counting method in plate after osmotic shock treatment were similar to the results of the direct observation method by means of SEM. But in the case of C. flavigena the latter method was much more reliable than the former, because the differences between the number of spheroplasts and protoplasts were not able to figure out on conuting the number of protoplast after osmotic shock tretment.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.11
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• pp.1471-1477
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• 2009

This study was conducted to examine the antioxidant activities of the extracts from aerial parts and roots of Syneilesis palmata. The ethanol extract of aerial parts showed the highest content of flavonoid compounds (31.72 mg/g), and the ethanol extract of roots has the highest content of total polyphenol compounds (68.11 mg/g). The water extract of S. palmata roots showed the highest xanthine oxidase inhibition of 99.29% and the ethanol extract of aerial parts showed 98.48% at 1.0 mg/mL. The ethanol extract of roots showed the highest value of nitrite scavenging ability of 70.89% at pH 1.2, SOD-like activity of 13.06% and electron donating ability of 98.58% at 1.0 mg/mL concentration. The effect of tyrosinase inhibition was found at only the ethanol extracts of roots (9.33%). We found that root extracts contain abundance polyphenol compounds and their antioxidant activities were greater than those of the extracts of aerial part.