• Macromolecular Research
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• v.13 no.6
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• pp.467-476
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• 2005

The main objective of this study was to develop and characterize pH-sensitive biodegradable polymeric materials. For pH-sensitivity, we employed three kinds of moieties: 2-amino-3-(lH-imidazol-4-yl)-propionic acid (H), N-[4-( 4,6-dimethyl-pyrimidin-2ylsulfamoyl)-phenyl]succinamic acid (SM), and 2- {3-[ 4-( 4,6-dimethyl-pyrim­idin- 2-ylsulfamoyl)-phenylcarbamoyl]-propionylamino} -3-(3 H - imidazol-4-yl)-propionic acid (SH). The pH -sensitive diblock copolymers were synthesized by ring opening polymerization and coupling reaction from poly(ethylene glycol) (MPEG), $\varepsilon$-caprolactone (CL), D,L-lactide (LA) and pH-sensitive moieties. The pH-sensitive SH molecule was synthesized in a two-step reaction. The first step involved the synthesis of SHM, a methyl ester derivative of SH, by coupling reaction of SM and L-histidine methyl ester dihydrochloride, whereas the second step involved the hydrolysis of the same. The synthesized SM, SHM and SH molecules were characterized by FTIR, $^{1}H$-NMR and $^{13}C$-NMR spectroscopy, whereas diblock copolymers and pH-sensitive diblock copolymer were characterized by $^{1}H$-NMR and GPC analysis. The critical micelle concentrations were determined at various pH conditions by fluorescence technique using pyrene as a probe. The micellization and demicellization studies of pH-sensitive diblock copolymers were also done at different pH conditions. The pH-sensitivity was further established by acid-based titration and DLS analysis.

• Journal of Food Hygiene and Safety
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• v.34 no.1
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• pp.65-72
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• 2019

This study was aimed at investigating the levels of the natural preservatives of benzoic, sorbic and propionic acids in cereal grains, nuts and seeds. Benzoic and sorbic acid were analyzed by high-performance liquid chromatography with a diode-array detector (HPLC-DAD) and further confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), whereas propionic acid was analyzed using a gas chromatography-flame ionization detector (GC-FID) and further confirmed by gas chromatography-mass spectrometry (GC-MS). Benzoic, sorbic and propionic acids were found in 44, 22, and 550 samples out of 702 samples, respectively. From the total of 702 samples. The concentrations of benzoic, sorbic and propionic acid were ranged from not detected (ND) to 23.74 mg/L, from ND to 7.90 mg/L, and from ND to 37.39 mg/L in cereal grains, nuts and seeds, respectively. The concentration ranges determined in this study could be used as standard criteria in the process of inspecting cereal grains, nuts and seeds for preservatives as well as to address consumer complaints or trade disputes.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.3
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• pp.249-250
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• 1989

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1883-1886
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• 2014

• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.2
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• pp.31-37
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• 1994

For a microbiological study of composting process, screening and assay method for biopolymer degrading enzymes and microorganisms were developed and for the study of the possibility of composting in anaerobic state, distribution of sulfate reducing bacteria which plays a final role in anaerobic degradation was investigated. Substrates used for the development of assay methods for biopolymer degradation are ${\beta}-glucan$, xylan, dextran, CMC(carboxy methly cellulose), casein, and collagen. These substrates were made insoluble by a cross-linking agent and linked with dye to make chromogenic substrates. ${\beta}-glucan$ and xylan substrates could substitute congo-red method for screening of polymer degrading microorganisms without damaging the colonies. Sulfate reducing bacteria contained in the sample sludge showed preference to lactic acid, propionic acid, butyric acid and formic acid and could use acetic acid and valeric acid.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.3
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• pp.41-51
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• 2012

Biohydrogen production and analysis of microbial community were attempted from the sugar manufacturing wastewater with anaerobic fermentation process. Addtion of nutrients ($N{\cdot}P$) into sugar manufacturing wastewater stimulates hydrogen production from 9.53 to $26.67m{\ell}$ $H_2/g$ COD. Butyric acid, acetic acid, lactic acid, and propionic acid were detected in the sample of the anaerobic fermentation process. Butyric acid/Acetic acid(B/A) ratio was increased 0.50 to 0.92 according to the nutrients addtion into the wastewater. Microbial community was analyzed as Clostridium sp. in the phylum of Firmicutes and Klebsiella sp., Erwinia sp., and enterobacter sp. of the class of $\gamma$-Proteobacteria. As the improvement of hydrogen production, Erwinia sp. was decreased and Klebsiella sp. was increased.

• Journal of Environmental Impact Assessment
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• v.30 no.2
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• pp.132-139
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• 2021

Laboratory-scale experiments were conducted to assess the effect of oxidative decomposition of polycyclic aromatic hydrocarbons (PAHs) in field soil using peroxy-acid. The study soil texture is sandy soil containing 19.2 % of organic matter at pH 6.8. Among polycyclic aromatic hydrocarbons (PAHs) in the study soil, the concentration of benzo(a)pyrene is 2.23 mg/kg which is three times higherthan the Korea standard level. Therefore benzo(a)pyrene was selected as the target study PAH for the treatment by peroxy-acid oxidation using peroxy-acid coupled with hydrogen peroxide, and the efficiency of the oxidative decomposition of benzo(a)pyrene was assessed for the different organic acids and dosages of an organic acid and hydrogen peroxide. Propionic acid among the tested organic acids showed the highest efficiency of benzo(a)pyrene reduction in the peroxyacid oxidation treatment and finally satisfied the Korea standard level.

• Korean Journal of Food Science and Technology
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• v.36 no.1
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• pp.129-133
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• 2004

The active compound responsible fer the anti-oxidant activity in Chinese cabbage kimchi were isolated and identified. The dichloromethane fraction of Chinese cabbage kimchi with the greatest anti-oxidant activity was used. Silica gel column chromatography, Sephadex LH-20 column chromatography, TLC, and Sep-pak catridge were used for isolating the active compounds and IR, EI-MS, GC-MS, $^{1}H-NMR$, $^{13}C-NMR$ were used to identify the structure of the isolated compounds. 3-(4'-Hydroxyl-3',5'-dimethoxyphenyl)propionic acid of molecular weight 226, which had 3.4 times greater free radical scavenging activity than Vit. C and significantly greater anti-oxidant activity against LDL oxidation than the control, was obtained, This active principle may be beneficial in preventing hyperlipidemia and artherosclerosis in human.

• Applied Biological Chemistry
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• v.50 no.1
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• pp.6-11
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• 2007

This study was carried out to evaluate the growth characteristics of Propionbacterium freudenreichii KCCM 31227 and production of organic acids in whey broth. Bacterial growth and increase rate of TTA (Total Titratible Acidity) were analysed. Log numbers of Propionibacterium freudenreichii KCCM 31227 was at the highest peak at 7.5${\times}10^7$ cfu/ml in fementation of 72 hr in 12% whey broth treated with low temperature long time method (60$^{\circ}C$, 30min) containing 1% yeast extract. TTA value of 12% whey broth treated with low temperature long time method and containing 1% yeast extract showed the highest peak at 5.2 in fermentation of 72 hr. The increase rate of cells and TTA in whey broth revealed almost the same tendency. Production of propionic and acetic acids showed higher value in the whey broth treated with low temperature long time method.

• Asian-Australasian Journal of Animal Sciences
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• v.4 no.1
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• pp.59-65
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• 1991

From the same harvest of Italian ryegrass (Lolium multiflorum, Lam.), hay(H), wilted silage(WS), pressed cake hay (PCH) and pressed cake silage (PCS) were prepared. These four preserved roughages were restrictedly fed to four goats attached with rumen fistula by $4{\times}4$ Latin square design to determine the effect of different physical and chemical properties of the roughages on the ruminal acid concentrations. Each goat was given a diet at 2% of the body weight daily in dry matter basis by separating into two equal portions. Half was given at 9 AM and the other half at 5 PM. Ruminal pH was reduced to around 5.5 within 30 minutes after feeding PCS and it was recovered above 6 in 1-2 hours after feeding. By feeding WS, ruminal pH was also reduced but never fell below 6. The two hays rather increased ruminal pH after feeding. The reduction of ruminal pH in the silage feedings was due to the high lactic acid content of the silages, because the highest ruminal lactic acid concentration was observed 30 minutes after feeding when the lowest ruminal pH was attained. While the ruminal VFA concentrations became the highest 1-2 hours after feeding. The ruminal acetic acid concentration fluctuated so much that no significant tendency was observed among the four dietary treatments. The ruminal propionic acid concentration was higher in feeding silages reflecting the initial high lactic acid concentration. As the result, acetic/propionic acid ratio was lower in the silage feedings than in hay feedings. Higher ruminal butyric acid concentration was observed in WS than in others.