• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.243-249
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• 2005

Esterification of lactic acid with alcohols catalyzed by Amberlyst-type ion exchange resins and sulfuric acid was carried out in a batch reactor with total /or partial recycle of distilled condensates, respectively. The esterification of lactic acid in the total-recycling reactor (n-butanol/lactic acid = 4, $100^{\circ}C$) was promoted by decreasing the residual water and increasing the mole ratio of n-butanol/lactic acid. Also, it was confirmed that methanol with simple structure and tert-butanol with superior substitution reactivity were more effective in increasing the conversion of esterification reaction, compared to ethanol, n-butanol, and iso-butanol. In a partial-recycling reactor (n-butanol/ammonium lactate = 4, $115^{\circ}C$), the conversion of ammonium lactate into butyl lactate with 1.0 wt% Amberyst-type resins was higher in comparison to that with 0.2 mol $H_2SO_4$ (per 1.0 mol ammonium lactate). The esterification was gradually occurred during the initial stage of reaction in the presence of solid catalyst, whereas the initial addition of $H_2SO_4$ did not affect the initial rate of esterification reaction because of ammonium sulfate formation by the neutralizing reaction of ammonium lactate with sulfuric acid.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.1-7
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• 2018

The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay is commonly used for analyzing the cell viability. In this study, effects of various solvents, different lights, and zinc protoporphyrin (ZnPP) on the chemical behavior of MTT formazan were investigated. The color response of MTT formazan in NaOH was highly pronounced; the absorbance of MTT formazan in 0.1 N NaOH at 550 nm was >2-fold higher than that in water, dimethyl sulfoxide (DMSO), methanol, and ethanol. MTT formazan in DMSO and NaOH (>0.1 N) was relatively stable under fluorescent and UV light at 365 nm; its rapid degradation was induced under UV light at 254 nm in all solvents. ZnPP degraded MTT formazan under light in a time- and concentration-dependent manner; MTT formazan in 0.1 N NaOH was the most sensitive to ZnPP, followed by DMSO. These results suggest that NaOH and DMSO might be suitable media for MTT formazan for monitoring photosensitizing properties.

• Korean Journal of Food Science and Technology
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• v.50 no.1
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• pp.111-116
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• 2018

Roasting process of grains modifies their physicochemical characteristics that affect flavor, color, taste, and textures, as well as composition of bioactive compounds. We roasted oats at different temperatures (150, 200, and $250^{\circ}C$) and for different time periods (15 and 30 min). The polyphenol and flavonoid contents in different solvent extracts (methanol, fermented ethanol, and water) were also investigated. The total polyphenol and flavonoid contents were highest in the methanolic extract (135 mg gallic acid equivalent/g and 29 mg catechin equivalent/g, respectively, at $250^{\circ}C/30min$ roasting) and increased with roasting time and temperature. In addition, the avenanthramides were most abundant as accessed ($266{\mu}g/g$) in the methanolic extract upon roasting at $200^{\circ}C$ for 15 min. The radical scavenging activities, using 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid scavenging, increased with roasting temperature and time. The roasting process may modify the physicochemical structure of oats, thereby, improving polyphenol extraction and antioxidant activity. The results of this study could be used for the manufacture of foods using roasted oats.

• Journal of Food Hygiene and Safety
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• v.29 no.1
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• pp.21-25
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• 2014

Formaldehyde and phenol used in the production of melamine-wares may be intended to come into foodstuffs. So this study investigated the migration of formaldehyde and phenol from 222 articles Articles were cups(14), bowls(75), plates(85), spoons(10), chopsticks(4), food trays(8), rice paddles(4), spatulas(9) and scoops(12). The food stimulants were 4% acetic acid, 20% ethanol, distilled water and n-heptane. Korea regulation (Standards and specifications for food utensils, containers and package) specifies migration limits for formaldehyde and phenol in food stimulants. Formaldehyde and phenol are restricted by 4 mg/L, 5 mg/L respectively. In all cases the migration of formaldehyde and phenol were below the limit set in Korea regulation. The level of formaldehyde and phenol migrated to food simulants were in the range of N.D~2.949 mg/L, N.D~0.078 mg/L respectively. These migration results of formaldehyde and phenol will provide a scientific basis for the safety management of melamine-wares.

• Korean journal of food and cookery science
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• v.21 no.2 s.86
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• pp.171-179
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• 2005

This study was investigated on antioxidative and antimicrobial activities of PSW(pomegranate seed water extract), PSE(pomegranate seed ethanol extract) and PSO(pomegranate seed oil). The extraction yields of PSW, PSE and PSO were 28.9, 13.0 and $4.9\%$, respectively. Total phenol contents of PSW, PSE and PSO were 47, 78 mg/g(dry basis) and 40 mg/g, respectively. Electron donating abilities of PSW, PSE and PSO at 1,000 ppm were 18.8, 28.5 and $9.7\%$, respectively. Antioxidative activities in Iinoleic acid substrates at 500 ppm were in order of PSE > $\alpha-tocopherol$ > PSW > PSO. Antioxidative activities in Iinoleic acid emulsion substrates at 200 ppm were in order of $\alpha-tocopherol$l > PSE > PSW > PSO. In antimicrobial activity, PSO showed growth inhibition effect against Micrococcus luteus, Salmonella enteritidis and PSW showed growth inhibition effect against Bacillus cereus, Escherichia coli. Whereas antimicrobial activity of PSE was not observed. The nitrite-scavenging abilities of PSW, PSE and PSO at 2,000 ppm were 27.5, 23.7 and $39.6\%$, respectively. And the SOD-like activities of PSW, PSE and PSO at 1,000 ppm were 15.9, 34.9 and $0.10\%$, respectively.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.157-161
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• 1996

Physicochemical and microbial characteristics of traditional kochujang (fermented hot pepper-soybean paste) collected from 55 households at different regions were investigated. The traditional kochujang contained $46.71{\pm}5.98%$ moisture, $46.87{\pm}8.83%$ total sugar, $11.77{\pm}3.90%$ crude protein, $15.01{\pm}6.48%$ salt, $27.52{\pm}7.32%$ reducing sugar, $0.26{\pm}0.15%$ amino nitrogen and $2.69{\pm}2.35%$ ethanol. The pH and titrable acidity were $4.60{\pm}0.23$ and $27.26{\pm}10.98\;ml/10\;g$, respectively. The average water activity of traditional kochujang were $0.79{\pm}0.04$. The Hunter L, a, and b values of kochujang were $16.03{\pm}2.89$, $20.42{\pm}4.37$, and $9.71{\pm}1.92$, respectively. The viable cell counts of aerobic, anaerobic bacteria and yeasts in the traditional kochujang were $1.02{\times}10^8{\pm}1.29{\times}10^8\;CFU/g$, $2.24{\times}10^7{\pm}3.90{\times}10^7\;CFU/g$ and $5.90{\times}10^5{\pm}2.25{\times}10^6\;CFU/g$, respectively. The kochujang collected from various regions showed quite strong liquefying and saccharogenic amylase and protease at different level by samples.

• Korean Chemical Engineering Research
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• v.43 no.5
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• pp.641-645
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• 2005

Using aqueous solution of 60% ethanol, the isoflavones contained in the Soybean (Chungsun, Korea), Tawon (Suwon, Korea), Jackbean (Hongsung, Korea), Soybean (Jilin, China), Black Soybean (Jilin, China), Kidneybean (Jilin, China) and Soybean (California, U.S.A.) were extracted. In this work, the pretreatment step was composed of agitation extraction, filtration, concentration, ultracentrifuge, and membrane filtration. The analysis by $C_{18}$ column was performed, and the mobile phase applied was linearly changed with A/B of 85/15-65/35 vol% for 50 min (A water/acetic acid, 99.9/0.1 vol%, B acetonitrile/acetic acid, 99.9/0.1 vol%). Among the soybeans tested, the total amounts of the four isoflavones (daidzin, genistin, daidzein, and genistein) extracted by the soybeans from Korea, China and U.S.A. were 1.37, 1.60, and 2.25 mg/g, respectively. It was also found that the total amount of aglycone of daidzein and genistein from soybean (American California) was $144{\mu}g/g$, which was the largest for the soybeans experimented.

• Journal of Radiation Industry
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• v.10 no.4
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• pp.189-192
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• 2016

$^{68}Ga$ has emerged as a promising candidate for non-invasive diagnostic imaging within Positron Emission Tomography (PET) because of its advantageous radiochemical characteristics ($t_{1/2}=68min$, ${\beta}^+$ yield ~89%). $^{68}Ga$ forms a stable chelation with various ligands and it is possible to be quickly and easily study using a $^{68}Ge/^{68}Ga$ generator. Commercial $^{68}Ge/^{68}Ga$ generators are chromatographic system using the inorganic materials such as alumina and tin dioxide which are employed as column matrixes for $^{68}Ge$. In this study, we tried out to make $^{68}Ge/^{68}Ga$ generator system with the $^{68}GeO_2$ microstructures for column matrix. $^{68}Ge$ tends to have stable bond with oxide as $^{68}GeO_2$ microstructures. The $^{68}GeO_2$ has been synthesized by hydrolysis of $GeCl_4$ (sol-gel method) and characterized by X-ray diffraction and scanning electron microscope for geometrical analysis. The stability of $GeO_2$ was tested using eluents with diverse solvents(water, ethanol and 0.1 N HCl). The radioactivity of $^{68}Ga^{3+}$ in eluate through $GeO_2$ was measured to prove a function as column material for a generator.

• Journal of agriculture & life science
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• v.43 no.3
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• pp.35-44
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• 2009

Antifungal activity reaction to Aloe peel and juice extracted by several solvents and concentrations against three plant pathogenic fungi as collectrichum gloeosporioides, Fusarium oxysporum, and F. solani were investigated. The Antifungal activity of Aloe extracts varied with the kinds of solvents. In case of C. gloesporioides and F. solani, it's the highest in water, second in methanol, and third in ethanol. It showed that Antifungal activity of Aloe peel and juice extracts based on concentration was much more excellent in juice extracts than peel extracts against C. gloeosporioides, F. solani. Effect of Antifungal against F. oxysporum by juice extracts did not appear at a concentration of $100{\mu}l/L$ and then shows 9.5% of inhibition rate at $100,000{\mu}l/L$ while against C. gloeosporioides it starts to react at $100{\mu}l/L$ and then reaches at 29.3% of the highest inhibition rate at a concentration of $100,000{\mu}l/L$ out of three plant pathogenic fungi. The effect of control efficacy against Fusarium wilt caused by F. oxysporum by juice extracts of foliar spray tends to increase and the more the concentration of juice extracts increases, the higher the effect of control efficacy against Fusarium wilt disease. Foliar spray at a concentration of 10g/L has a 62% of control efficacy compared with control treatment, which foliar spray of Aloe juice extracts can be the more effective method in order to prevent Fusarium wilt disease caused by F. oxysporum.

• Journal of agriculture & life science
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• v.44 no.3
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• pp.61-67
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• 2010

This study was conducted to investigate the antioxidant activities and ginsenoside compositions of 4-year-old cultured ginseng roots (4CGR), 4-year-old mountain ginseng roots (4MGR) and leaves (4MGL), and 8-year-old mountain ginseng roots (MGR) and leaves (8MGL). Ginseng root and leaves were extracted with water and 80% ethanol. Crude saponin content of 4CGR was 3.85% (d.b.) and the contents of 4MGR, 4MGL, 8MGR and 8MGL were 6.75, 8.57, 6.53 and 7.54% (d.b.), respectively. 4CGR showed the highest content of ginsenoside-$Rh_1$ (6.07 mg/g), 4MGR showed the highest content of ginsenoside-$Rb_1$ (11.63 mg/g), 4MGL showed the highest content of ginsenoside-Re (24.35 mg/g), 8MGR showed the highest content of ginsenoside-$Rh_1$ (19.77 mg/g), and 8MGL showed the highest content of ginsenoside-Re (20.43 mg/g). Total antioxidant activity (AEAC) was ranged from 5.56 at 4MGR to 20.67 mg AA eq/g at 8MGL.