• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.22-34
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• 1998

The purpose of this study is to develop biosensor for determination of glucose, lactate, and ethanol in foods and food-stuffs simultaneously. The multiple cathode system was prepared with an oxygen electrode having one anode and hexagonal cathode. Glucose oxidase, mutarotase, lactate oxidase, alcohol oxidase and catalase were used for immobilization to determine glucose, lactate, and ethanol. These components including ethanol were simultaneously determined by the immobilized enzymes in the multiple cathode system. The determination of the components by enzyme sensor was based on the maximum slope of oxygen consumption from enzyme reaction of each sensor part. The response time for analysis was 1 min. The optimum condition for glucose, lactate and ethanol sensor was found to be 0.1 M potassium phosphate buffer, pH 7.0 at $40^{\circ}C$. Interferences of various sugars and organic acids were investigated. Less than 10% of error was found in determination of the components except organic acids. This difference was compensated by the modified equation. This system was confirmed by conventional methods. It was concluded that the multiple cathode system of this study is for an effective method to determine sugar, organic acid, ethanol simultaneously in foods.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.866-870
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• 1995

This study was conducted to determine the effect of soluble polysaccharides and indigestible polysaccharides on the digestibility of casein in vitro and the structure of polysaccharide. The digestibility of casein by trypsin in vitro was reduced to $80{\sim}89%$ and $69{\sim}99%$ by high molecular soluble polysaccharide (HMS-P) and low molecular insoluble polysaccharide (LMI-P) prepared from buckwheat, respectively. The digestibility of casein by chymotrypsin was reduced to $63{\sim}88%$ and$71{\sim}79%$ by HMS-P and LMI-P, respectively. But casein digestibiliy by trypsin and chymotrypsin was slightly reduced by LMS-P. The casein hydrolyzates inhibited by HMS-P gave a main peak in the void volume on Sepadex G-100, but the peak in the total volume was only appeared in case of LMS-P having no inhibito교 effect. It was suggested that the HMS-P was consisted of 4-linked and 4,6-dissubstituted glucose from the structural analysis by GC.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.797-802
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• 2003

Structured lipids (SL) were synthesized by esterification of corn oil and conjugated linoleic acid (CLA) in a continuous packed-bed column reactor. The effects of flow rate, reaction temperature, and substrate molar ratios were studied. The reaction was catalyzed by TL IM (immobilized lipase from Thermomyces lanuginosa). Results of triacylglycerol (TAG) analysis by GC showed that the incorporated CLA isomers were mainly cis9, trans11- and trans 10, cis12-CLA. Slower flow rates yielded higher incorporation, and maximum incorporation of CLA was obtained with a molar ratio of 1:3 (corn oil: CLA) at a temperature of $55^{\circ}C$. The obtained SLs had iodine values ranging from 120 to 128. The SLs were composed of TAG $(98{\sim}99%)$, 1,2- and 1,3-diacylglycerol ($0.7{\sim}1.3%$), and a small amount of monoacylglycerol.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.656-663
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• 2001

The most representative nitrosamine derived from nicotine, nitrosamine-4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone(NNK), has been reported to cause lung cancer in A/J mice. It has been also demonstrated that NNK-induced lung tumorigenesis involves $O^6-methylguanine(O^6MeG)$ formation, leading to $GC\;{\rightarrow}\;AT$ transitional mispairing during DNA replication. Our in vitro experiment, modified from the method of DBA assay, examined the ability of phyto-extract mixture to inhibit the metabolism of nicotine to nitrosamines. The production of nitromorpholine from morpholine was inhibited about 75% at the concentration of 20 mg/mL of phyto-extract mixture, which was lower than vitamine C and green tea powder. NNK, which is a pro-carcinogen in laboratory animals, is hydroxylated primarily in liver and lung by CYP 1A2, 2A6 and 3A4. A critical phase. of NNK activation is its change to an unstable metabolite methyl-diazohydroxide via CYP-mediated ${\alpha}-hydroxylation$; and then it provides a methyl group to the DNA to form DNA adducts which can easily induce mutations. $Aroclor^R$ 1254 was used to induce CYPs in the liver of a Sprague-Dawley rat. The ability of various test samples to inhibit CYPs that participate in NNK activation was evaluated, following the removal of the liver from the rat. Microsomal CYPlA2 catalyzing the conversion of NNK into strong carcinogenic chemicals was inhibited more efficiently by phyto-extract mixture than green tea powder. These results indicate that phyto-extract mixture can be used to reduce $O^6MeG$ DNA adducts for chemoprevention.

• The Korean Journal of Pesticide Science
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• v.3 no.2
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• pp.8-18
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• 1999

The degradation of a fungicide, $^{14}C$-propiconazole, in sterile and nonsterile soil from different depths was investigated. $^{14}C$-propiconazole plus propiconazole standard was treated on the soil at the rate of 7.55 mg/kg and the soil was incubated at $25^{\circ}C$ for 20 weeks. The amounts of $^{14}CO_{2}$ solvent extractable and non-extractable $^{14}C$, and degradation products of $^{14}C$-propiconazole were investigated during incubation time. The relative amounts of $^{14}CO_{2}$ released in the sterile and nonsterile soils were ranging from 0.7 to 1.3% and from 4.8 to 7.6% of applied $^{14}C$, repectively. The amounts of solvent non-extractable residues in the sterile and nonsterile soils were ranging from 11.2 to 22.1% and from 22.2 to 41.9% of of applied $^{14}C$, repectively. The amounts of solvent non-extractable residues were increased with incubation time and most of $^{14}C$ were detected in the humin fraction. The hydroxylated and ketone compound were confirmed as a degradation products of propiconazole by GC/MS analysis, whereas parent compound was detected in sterile soil, which suggested that propiconazole was not degraded biologically under the sterile soil. From the results of volatilization, mineralization and degradation of propiconazole, propiconazole was stable chemically and bilogically in soil.

• The Korean Journal of Pesticide Science
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• v.15 no.4
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• pp.389-400
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• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Journal of Microbiology and Biotechnology
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• v.21 no.9
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• pp.893-902
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• 2011

Endophytic fungi are little known for their role in gibberellins (GAs) synthesis and abiotic stress resistance in crop plants. We isolated 10 endophytes from the roots of field-grown soybean and screened their culture filtrates (CF) on the GAs biosynthesis mutant rice line - Waito-C. CF bioassay showed that endophyte GMH-1B significantly promoted the growth of Waito-C compared with controls. GMH-1B was identified as Penicillium minioluteum LHL09 on the basis of ITS regions rDNA sequence homology and phylogenetic analyses. GC/MS-SIM analysis of CF of P. minioluteum revealed the presence of bioactive $GA_4$ and $GA_7$. In endophyte-soybean plant interaction, P. minioluteum association significantly promoted growth characteristics (shoot length, shoot fresh and dry biomasses, chlorophyll content, and leaf area) and nitrogen assimilation, with and without sodium chloride (NaCl)-induced salinity (70 and 140 mM) stress, as compared with control. Field-emission scanning electron microcopy showed active colonization of endophyte with host plants before and after stress treatments. In response to salinity stress, low endogenous abscisic acid and high salicylic acid accumulation in endophyte-associated plants elucidated the stress mitigation by P. minioluteum. The endophytic fungal symbiosis of P. minioluteum also increased the daidzein and genistein contents in the soybean as compared with control plants, under salt stress. Thus, P. minioluteum ameliorated the adverse effects of abiotic salinity stress and rescued soybean plant growth by influencing biosynthesis of the plant's hormones and flavonoids.

• 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.37 no.2
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• pp.190-194
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• 2008

Physicochemical properties of the green tea component enriched mushroom (Flammulina velutipes) were investigated. The yield of mushroom was highest with green tea powder untreated sample and the yield was decreased by the addition of green tea powder. However, hardness was increased by the addition of green tea powder. Analysis of catechins and caffeine in mushrooms showed that catechins were not transferred into mushrooms, whereas caffeine content was increased. The content of total polyphenol in mushroom was not affected by the addition of green tea powder and crude catechins. Analyses of aroma patterns using the electronic nose based on GC with SAW sensor showed that new peaks occurred from 3 to 6 sec in green tea added mushroom. This study showed that functional components and quality of mushroom were possibly improved by incorporating green tea powder in growth medium.

• Korean journal of applied entomology
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• v.51 no.4
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• pp.469-477
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• 2012

Ostrinia larvae feed the pods and stem of red bean and seriously damage the bean production from farmers. In this study we investigated biological and developmental characteristics including field collection, host feeding preference, artificial rearing diet, morphological and molecular taxonomical identification, and pheromone analysis for an Ostrinia sp. in Korea. The male adults have massive tibia in the middle legs and 3-lobed uncus in the genitalia. The partial nucleotide sequences of mitochondrial cytochrome oxidase I (COI) and II (COII) were not corresponded to those DNA sequences from other Ostrinia species reported previously in Japan and China. Host plants for this species are also different from the previous species reported. In the gas chromatography (GC) analyses, (Z)-9-tetradecenyl acetate was not detected from the pheromone gland of our species while the component as a sex pheromone was found in O. zaguliaevi and O. zealis, With taken results, we conclude this Ostrinia species in Korea is Ostrinia scapulalis or closely related species. When larvae collected in a fall were incubated in the outdoor condition, they emerged to adult between June and July in the next year. The result indicates that the winter diapause could be started in late larval stage. In addition, we developed a semi-synthetic artificial diet adopted for mass rearing of the O. scapulalis in laboratory.