• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

• Korean Journal of Food Science and Technology
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• v.30 no.3
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• pp.638-643
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• 1998

The volatile flavor components in Takju made from mashed glutinous rice and barley rice were identified by GC and GC-MS using polar column. Twenty eight kinds of flavor compounds including 10 alcohols, 9 esters, 2 acids, 7 aldehydes were identified. At the beginning of fermentation 14 kinds of volatile components were detected and the kinds of volatile components were increased up to maximum after fermentation for 16 days. The contents of volatile components in the sample made from glutinous rice contained slightly higher than the sample made from barley rice. Ethyl alcohol, n-propyl alcohol, iso-amyl alcohol, n-hexyl alcohol, hexenyl alcohol, 2-phenylethyl alcohol, ethyl acetate, ethyl succinate, 2-phenylethyl acetate, butyic acid, benzaldehyde and 3-methoxybenzaldehyde were detected in the both of the sample throughout the fermentation process. Five kinds of aldehyde including ethyl propionate, iso-amyl acetate, ethyl caprylate and ethylphenyl acetate were detected only in the sample fermented for 16 days. The main components of the both sample were ethyl alcohol, iso-amyl alcohol, 2-phenylethyl alcohol, 2-phenylethyl acetate, hexenyl alcohol and iso-butyl alcohol. Besides ethyl acetate and benzaldehyde from glutinous rice Takju and hexenyl alcohol from barley rice Takju were found as main components.

• Food Science and Preservation
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• v.14 no.3
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• pp.323-327
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• 2007

Moderate consumption of maesil(Prunus mune) was associated with pharmaceutical and physiological effects on human health. The object of this study was to determine the inhibitory effects of Prunus mune extracts(PME) on food spoilage microorganisms. PME was found to have an antibacterial effect on Colletotrichum fragariae. The hydrophilic fractions of PME showed more effective inhibition than did the hydrophobic fractions. In addition, the hydrophilic fractions of PME seemed to inhibit(12-40%) metabolic enzymes related to energy production, including glucose-6-phosphate dehydrogenase, succinate dehydrogenase, malate dehydrogenase, and hexokinase. Our data suggest that hydrophilic components of PME might control food spoilage microorganisms because of suppression of membrane enzymatic function.

• Korean Journal of Environmental Agriculture
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• v.6 no.2
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• pp.94-100
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• 1987

Plant mitochondria, irradiated with blue-colored $sunlight(350{\sim}500nm)$ under aerobic and anaerobic conditions, were assayed as to the electron transfer activity of respiratory enzyme system, and compared with those irradiated with orange-colored light(white sunlight minus blue-colored light). The respiratory activity of mitochondria was most seriousely inhibited by illumination with blue-colored light under aerobic condition. Deaeration of mitochondrial suspension resulted in substantial decrease of the photoinhibition by blue-colored light. Meanwhile, orange-colored light demonstrated much less effectiveness-almost ineffectiveness-in causing the inhibition of mitochondrial respiration system. The results of enzymatic assay revealed a strong possibility that FMN in NDH and heme group at least in cytochrome c oxidase, but not FAD in SDH, are the photodynamic sensitizers in mitochondrial inner membrane. Also worthwhile to note is the significant difference from the others of SDH in its photoinhibitory response to the light quality of visible light; that the inhibition of SDH by irradiation was not affected by atmospheric condition and that orange-colored light gave rise to considerable extents of inhibition to the enzyme. This observation was tentatively interpreted in terms of photosensitized reaction not involving molecular oxygen possibly catalyzed by Fe-S centers in the enzyme. The superoxide production and the membrane peroxidation of mitochondria under various treatments also indicated that there was blue-light photodynamic reaction in mitochondria involving active oxygens.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.207-215
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• 2010

The purpose of this research is to draw the bacterial community difference between Korean and Chinese kimchi for future use in the confirmation of kimchi origin. Initial fermentation stage kimchi samples (above pH 5) were used for the analysis of bacterial diversity. From 26 Korean kimchi samples, 1,017 strains in the 45 genera and from 22 Chinese kimchi samples, 842 strains in the 54 genera were isolated with use of marine medium, nutrient medium, succinate minimal medium (SMM), leuconostocs selective medium (LUSM) agars. In the order of isolated numbers, Bacillus, Weissella, Leuconostoc, Pseudomonas, and Lactobacillus genera and Bacillus, Weissella, Lactobacillus, Pseudomonas, Serratia, and Enterobacter genera were predominated in Korean and Chines kimchi, respectively. Among the isolated lactic acid bacteria, Weissella spp. were isolated most dominantly owing to the biased growth of Weissella spp. on LUSM agar. Species in the genera Leuconostoc and Lactobacillus were the next frequently isolated LAB from Korean and Chinese kimchi, respectively. Weissella confusa was isolated only from Korean kimchi and W. soli and Serratia proteamculans were isolated only from Chinese kimchi. They have a possibility to be used as target bacteria to differentiate Korean kimchi from Chinese kimchi.

• Microbiology and Biotechnology Letters
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• v.16 no.4
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• pp.275-281
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• 1988

To develop cellulase and xylanase-producing strain by protoplast fusion, alkalophilic Bacillus sp. F204 and K17 were treated with NTG(N-methyl-N'-nitro-N-nitrosoguanidine) and isolated anti-biotics resistant strains of S20 (Km$^r$ , Cm$^r$) and G70 (Str$^r$). The frequency of protoplast formation was about 95% when cells of mid-log phase were treated with 200$\mu\textrm{g}$/ml Iysozyme at 37$^{\circ}C$ for 30-45 minutes. Under addition of 0.4-0.5M sodium succinate, 0.5% casamino acid, 1.5% polyvinylpyrrolidone, 25mM MgC1$_2$ and 50mM CaC1$_2$ to the regeneration medium, the regeneration frequency of Bacillus sp. F204 and K17 was 24.9% and 26.2%, respectively. The fusion frequency was 6.6$\times$10$^{-6}$ in the presence of 30% polyethylene glycol 6000 containing 50mM $Ca^{++}$ at 45$^{\circ}C$ for 5 minutes. Cellulase complex and xylanase activities of fusant were compared with parental strains.

• Korean journal of food and cookery science
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• v.4 no.2
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• pp.21-30
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• 1988

To study the optimum fermentation and aging conditions for preparation of Andong Sikhe which is consumed in the northern Kyungbuk province as a traditional beverage, Sikhe were fermented and aged at $12^{\circ}C$ for 48, 60 and 72hrs and fermented at 40, 50. and $60^{\circ}C$ for 2, 3, and 4hrs and then aged at $12^{\circ}C$ for 20 hrs, Non-volatile organic acids and free sugars were analyzed by GC and HPLC, respectively, and sensory test was performed. Sikhe fermented at $40^{\circ}C$ for 3hrs and aged at $12^{\circ}C$ for 20hrs was evaluated the most favorable one by sensory test. This Sikhe had the lowest pH 4.6~4.7 among sample and 14.6% of sugar. The sugar content was lower than those of Sikhe Fermented at $50^{\circ}C$ and $60^{\circ}C$. In organic acid analysis, the concentration of malate 67.53%/mg in this Sikhe was the highest. Lactate, succinate and maleate were produced more in this Sikhe than in any other ones. Oxalate which was existed before fermentation was not found in the Sikhe, and a small amounts of citrate and fumarate were produced. In sugar analysis, maltose was dominant 11.56%, glucose 1.25% and fructose 0.45%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.814-824
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• 2018

This study was conducted to investigate VFA, monosaccharides and metabolites in rumen fluid according to feeding methods. Three castrated Hanwoo steers were used to the $3{\times}3$ Latin square design, 10 day for the diet adaptation period. VFA and monosaccharides which were not detected by HPLC and HPAEC however, those were detected by $^1H-NMR$. Among the metabolites measured by $^1H-NMR$ carbohydrate metabolites, pyruvate was detected only in the rumen fluid before feeding and succinate was detected before and after feeding rumen fluid. In amino acid total 9 metabolites were detected. In lipid metabolites, ethylene glycol was significantly higher (P<0.05) in before feeding Con group. In aliphatic acylic metabolite, trimethylamine N-oxide was no significant difference observed compare to Con group. In this study, many metabolites were observed in the rumen fluid by $^1H-NMR$, and it confirmed that rumen metabolic products were changed by feeding methods.

• Journal of the Korean Wood Science and Technology
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• v.32 no.5
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• pp.29-38
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• 2004

In this study, we investigated the thermal properties of corn-starch filled polybutylene succinate-adipate (PBS-AD) bio-composites. Thermal analysis (TA) is used to describe the analytical method for measuring the chemical property and weight loss of composite materials as a function of temperature. The thermal stability of corn-starch was lower than that of pure PBS-AD. As corn-starch loading increased, the thermal stability and degradation temperature of the bio-composites decreased and the ash content increased. It can be seen that the degree of compatibility and interfacial adhesion of the bio-composites decreased because of the increasing mixing ratio of the corn-starch. As the content of corn-starch increased, there was no significant change in the glass transition temperature (T_g) and the melting temperature (T_m) for the bio-composites. The storage modulus (E') and loss modulus (E") of the corn-starch flour filled PBS-AD bio-composites were higher than those of PBS-AD, because of the incorporation of corn-starch increased the stiffness of the bio-composites. At higher temperatures, the decreased storage modulus (E') of bio-composites was due to the increased polymer chain mobility of the matrix polymer. From these results, we can expect that corn-starch has potential as a reinforcing filler for bio-composites. Furthermore, we recommend using a coupling agent to improve the interfacial adhesion between corn-starch and biodegradable polymer.

• Journal of Microbiology and Biotechnology
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• v.6 no.2
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• pp.103-109
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• 1996

Mn(II)+succinate decreased the carotenoid formation of the yeast Phaffia rhodozyma, probably by scavenging $O_2$. When duroquinone (DQ), an internal and external $O_2$ generator, was added to medium, P. rhodozyma produced more amount of carotenoids. The increased carotenoid production was destroyed by oxygen radical (OR) scavengers, ascorbate+Cu(II) and dimethylsulfoxide. When sub-lethal concentrations of $H_2O_2$ , an external OR source, and antimycin, an internal OR inducer, were used, the effect of $H_2O_2$ on carotenoid formation and composition was less significant than that of antimycin. Addition of superoxide dismutase, an external OR remover, rescued cells from death caused by the high concentration of DO. In this condition, the yeast culture showed an increase in carotenoid content. Addition of DQ into P. rhodozyma culture in the stationary phase did not increase carotenoid production. Therefore, carotenoid formation was stimulated by internal ORs in the growing yeast. It was probably due to release of catabolite repression on carotenogenesis in the yeast. Aeration was important for carotenoid production but was not as effective as the internal OR producer, DQ.