• Journal of the Korean Chemical Society
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• v.55 no.4
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• pp.715-718
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• 2011

• Applied Chemistry for Engineering
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• v.31 no.5
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• pp.475-480
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• 2020

Chelates synthesized with Cu(II) ion and lactic acid or chitosan were applied to the hydrolysis of organophosphate simulant, DFP (diisopropyl fluorophosphate). Under the homogeneous reaction condition, Cu(II)-lactic acid chelate hydrolyzed DFP with the half life time of 37.1 min. Cu(II)-LMWS chitosan chelate was synthesized with 1 kDa molecular weight of chitosan, which showed low solubility, and then crystallized. The half life time for hydrolyzing DFP using Cu(II)-LMWS chitosan was 32.9 h indicating that the reaction rate is enhanced as much as 16 times more than that of using 18 kDa chitosan-Cu(II) complex. Under the homogeneous reaction condition, the half life time of Cu(II)-LMWS chitosan was 8.75 h. Therefore, we found out that the solubility of Cu(II)-LMWS chitosan makes the difference in the reaction rate as much as 4 times.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.1
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• pp.63-69
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• 1987

Silk fibroin is likely to be hydrolyzed by acids or alkalies at high temperature, and the degree of the hydrolysis has been inferred from the changes in tensile strength and elongation. But, in this experiment, it was intended to infer that from the quantitative changes in terminal aminp group content as well as in tensile strength and elongation. Silk yarn was treated with boiling water, hydrochloric acid, and sodium hydroxide under various conditions. The boiling water somewhat degraded silk fibroin. Silk yarn treated with sodium hydroxide contained more terminal amino group than that treated with hydrochloric acid. This result agreed fairly well with the loss in weight, tensile strength, and elongation: the terminal amino group content increased with the decrease of tensile strength, elongation, and weight. The damage by sodium hydroxide to the silk fibroin was greater than that by hydrochloric acid.

• Applied Chemistry for Engineering
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• v.5 no.1
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• pp.114-120
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• 1994

Esterolysis reactions of PNPDPP (p-nitrophenyldiphenylphosphate) by DCI ( dichloroisocyanuric acid sodium salt) in borate buffer pH8.0 micellar phase were studied. The rate of hydrolysis reaction was rapidly increased by adding cationic surfactants, CTAC (cetyltrimethylammonium chloride) or CTAB (cetyltrimethylammonium bromide), to the DCI solution. Especially in CTAB micellar system, the N-Cl bond of DCI was transformed to the N-Br bond during the reaction.

• Journal of Life Science
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• v.15 no.1 s.68
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• pp.9-14
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• 2005

Batch enzymatic hydrolysis of egg yolk protein by protease was carried out at laboratory scale coupled to an ultrafiltration module. Effect of ethanol concentrations on the performance of enzymatic hydrolysis was studied to determine the optimum condition of recovery of hydrolysate. The enzymatic hydrolysis was conducted stepwise with following conditions, $50^{\circ}C$, pH 10.0 and pH 6.5. Ethanol concentration was changed from 10 to $40\%$ (w/w). As ethanol concentration was increased, the recovery yield of total solid and protein in enzymatic hydrolysate was also increased. The content of sialic acid and protein in hydrolysate was independent of ethanol concentration. We also investigated the effect of ethanol concentration on the performance of ultrafiltration. As the concentration of ethanol in yolk protein was increased, the recovery yield of product was increased. Ultra­filtration of egg yolk protein hydrolysate was conducted to increase the content of sialic acid. Four ultrafiltation modules were used in this study, and we evaluated the performance of the UF modules. When Amicon module was used, the recovery percentage of total solid in retentate was $6.0\%$, which is the highest among the modules used. In spite of the difference in the recovery yield of total solid, the purity of sialic acid in retentate was about $2.0\%$, which was 5 times higher than that in feed. It was concluded that the recovery yield and the purity of sialic acid did not correlate with the types of modules and the size of MWCO.

• Journal of Korean Society of Forest Science
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• v.79 no.4
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• pp.376-387
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• 1990

A research effort has been made to determine soil buffer capacity in forest soils nearby urban and industrialized regions. Buffer capacities of soils from four regions were measured by different pH levels of artificial acid precipitation. The following conclusions have been drawn in response to the overall research objectives. Soil Suffer capacity was the highest in Kangwondo followed by Uisan, Yeochon and Seoul when simulated acid precipitation were treated at the level of pH 3.0-5.7. With the acid precipitation treatment below pH 2.0 level, however, the capacity dropped seriously with no significant differences between the regions. In Kangwondo region soils weathered from granite and limestone showed significant differences in the buffer capacities. Soil collected in Seoul and Ulsean revealed that the capacities tended to increase with the distance from the pollution sources when treated at pH 3.0, 4.5 and 5.7 level of acid precipitation. The major mechanism of soil buffer observed during simulated acid precipitation experiment was canon exchange for Kangwondo forest soils. In Seoul region canon exchange also played an important role in soil buffering under artificial acid precipitation between 3.0 and 5.7 pH levels, yet under pH 2.0 level aluminum and silicate hydrolysis. In Ulsan canon exchange was a msjor determinant for the buffer capacity above pH 4.5 level, between pH 3.0-4.5 aluminum hydrolysis and below pH 3.0 aluminum and silicate hydrolysis. In Yeochon silicate hydrolysis led buffer capacity above pH 4.5 and below pH 4.5 aluminum hydrolysis.

• Journal of Life Science
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• v.25 no.7
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• pp.795-800
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• 2015

Oyster is a nutritionally good food ingredient. Also, oyster is used to make source for taste and flavor. This study tried to investigate optimal condition of hydrolysis of oyster and oyster cooking drip for better amino acid content to make good taste and flavor. And then this study characterized hydrolysate of oyster and oyster cooking drip. Enzymes are Acalase, Flavourzyme, Neutrase, and Protamax. The optimal condition for the highest enzyme activity is given by the company. Under the best condition of each enzymes, they react with the homogenized oyster and oyster cooking drip for 0.5, 1.0, 1.5, 2, 4, 6 hr. The degree of oysters’ hydrolysis is 13.2±0.1%. But, in the case of using enzyme, the rate of hydrolysis sharply increased as time went on during 2 hr. After 8 hr, the rate is 36.9~40.5%. Protamax showed 27.4±0.4% of hydrolysis rate in 2 hr. And the degree of oyster cooking drop hydrolysis is 42.7±0.1%. The highest of hydrolysate concentration is 72.1±0.1% using protamax. In the case of oyster, it has a similar tendency of all enzymes. Otherwise, the hydrolysate of oyster cooking drip had a difference among the enzymes. Composition of free amino acid of hydrolysate using protamax was investigated how much time showed highest rate of hydrolysis to find best amino acid composition. Hydrolysis using Protamax during 6 hr is selected for best condition.

• Journal of the Korean Society of Food Culture
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• v.24 no.1
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• pp.84-89
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• 2009

This paper was conducted to evaluate aglycones and carbohydrates produced by acid hydrolysis of three potato glycoalkaloids [(PGA); ${\alpha}$-chaconine, ${\alpha}$-solanine, and demissine] in potatoes. Standard solanidine and demissidine were dissolved in 1N HCl and then heated at $100^{\circ}C$ for 10-120 min. Solanidine was rapidly decomposed during acid hydrolysis and one peak that was identified as solantherene ($M^+$=379) by GC-MS was detected. The transformation solanidine to solanthrene was approximately 50% complete after 10 min, approximately 90% complete after 60 min and 100% complete after 120 min. Demissidine was hydrolyzed using the same method that was used to hydrolyze the solanidine. However, demissidine produced only one peak upon GC-MS ($M^+$=399) analysis and was found to be very stable at increased temperatures. Acidy hydrolysis of ${\alpha}$-chaconine, ${\alpha}$-solanine and demissine resulted in the decomposition of ${\alpha}$-chaconine and ${\alpha}$-solanine to solanidine and solanthrene, respectively. Therefore, this hydrolysis method should not be utilized to produce PGA combining with solanidine as aglycone. The individual carbohydrates produced by the two PGAs by hydrolysis were very stable at increased temperatures; therefore, it was possible to quantify these PGAs based on calculation of the individual carbohydrate content. Conversely, because demissidine produced by the hydrolysis of demissine was extremely stable at increased temperatures, it was possible to quantify the PGA based on the aglycone produced by hydrolysis.

• Culinary science and hospitality research
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• v.18 no.1
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• pp.15-26
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• 2012

The objective of this study is to optimize enzymatic hydrolysis of cooked krill by using Alcalase. To optimize krill hydrolysis on such dependent variables as TCA, DPPH-scavenging, and Fe-chelating activities by using Alcalase, independent variables of hydrolysis pH and temperature were investigated Their formulas and three dimensional graphs were obtained by using SAS and Maple softwares, respectively. For comparison of general composition of raw krill, its contents of moisture, crude protein, crude fat, and ash were 17.48%, 53.74%, 15.66%, and 10.21%, respectively, and for cooked krill, its contents were 4.80%, 71.84%, 5.26%, and 15.09%, respectively. The composition of fatty acids for cooked krill was similar to that of raw krill. The most abundant fatty acid was palmitic acid(16:0) and the following order was oleic acid(18:1), eicosapentaenoic acid (20:5), palmitoleic acid(16:1), and docosahexaenoic acid(22:6). For DH optimization of hydrolysates from cooked krill, its result was pH 8.5 and $66.6^{\circ}C$ hydrolysis temperature for the maximum DH of 29.4% For DPPH-antioxidative optimization of hydrolysates from raw krill, its maximum result of 27.1% was obtained in the hydrolysis condition of pH 7.4 and $67.5^{\circ}C$. For Fe-chelating optimization of hydrolysates from cooked krill, its maximum result of 24.9% was in the condition of pH 8.7 and $65.5^{\circ}C$. These results can be used for basic data for using krill products and other fish products as bioactive ingredients.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.141-148
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• 2012

In order to study the utilization of brown seaweed Laminaria japonica as an alternative renewable feedstock for bioethanol production, the properties of acid hydrolysis and ethanol fermentation were investigated. The acid hydrolysis enhanced the final yield of fermentable sugars, which led great increase of ethanol productivity. The maximum yield of reducing sugars reached 135 mg/g-dry Laminaria japonica after 1.0N sulfuric acid-hydrolysis at $130^{\circ}C$ for 6 h. The Saccharomyces cerevisiae (ATCC 24858) could ferment $C_6$-sugars like glucose, galactose and mannose into ethanol, but not $C_5$-sugars like arabinose and xylose. Optimal fermentation time varied with sugars; 48 h for glucose, 72 h for galactose, and 96 h for mannose. Nevertheless, the ethanol yield from the hydrolysate reached 242 mg/g-dry Laminaria japonica after fermentation by the S. cerevisiae at $35^{\circ}C$ for 96 h, which corresponds to approximately 4 times more than the theoretical yield from total reducing sugars in the hydrolysates. It indicates that the non-reducing sugars or oligosaccharides dissolved in the hydrolysate played an important role in producing bioethanol. The ethanol concentration linearly increased from 2.4 to 9.2 g/L, while the ethanol yield per dry weight of biomass decreased from 242 to 185 mg/g, with increasing the ratio of biomass to acid solution from 1 to 5% (w/v). The bioethanol yield estimated was approximately 7,400~9,600 kg/ha/year, and indicated that Laminaria japonica is a promissing feedstock for bioethanol production.