• KSBB Journal
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• v.24 no.3
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• pp.267-272
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• 2009

During a dilute acid hydrolysis, degradation products are formed or liberated by pre-treatment of lignocelluloses depend on both the biomass and the pretreatment conditions such as temperature, time, pressure, pH, redox conditions, and addition of catalysts. In lignocellulosic biomass, sugars can be degraded to furfural which is formed from pentoses and 5-hydroxymethulfurfural (HMF) from hexoses. 5-HMF can be further degraded, forming levulinic acid and formic acid. Acetate is liberated from hemicellulose during hydrolysis. Some decomposed compounds hinder the subsequent bioconversion of the solubilized sugars into desired products, reducing conversion yields and rates during fermentation. In the present work, samples of rapeseed strawwere hydrolyzed to study the optimal pretreatment condition by assessing yields of sugars and decomposed products obtained under different reaction conditions ($H_2SO_4$ 0.5-1.25% (w/w), reaction time 0-20 min and temperature range 150-220 C). A careful analytical investigation of acid hydrolyzate of rapeseed straw has not yet been undertaken, and a well-closed mass balance for the hydrolyzate in general is necessary to verify the productivity and economic predictions for this process.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.434-437
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• 1975

By fractional crystallization D-mandelic acid salt of diethyl-dl-1-aminobenzylphosphonate prepared from benzaldehyde, diethylphosphite and ammonia at the atmospheric pressure, gave diethyl(-)-1-aminobenzylphosphonate. (+)-1-Aminobenzylphosphonic acid was obtained by acidic hydrolysis of diethyl(-)-1-aminobenzylphosphonate hydrochloride.

• KSBB Journal
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• v.30 no.2
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• pp.53-57
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• 2015

In this study, the production of total reducing sugar from macro green-algae Enteromorpha intestinalis by enzymatic hydrolysis was investigated. As a result of enzymatic hydrolysis using 13 kind commercial enzymes, the highest yield of 8.75% was obtained from Viscozyme L, which is multi-enzyme complex such as cellulase, arabanase, beta-glucanase, hemicellulase and xylanase. As a control, only 0.33% and 0.27% yield were obtained from 1% sulfuric acid and 0.05 M citrate buffer (pH 4.8), respectively. In the case of enzyme mixture, the mixture of $Viscozyme^{(R)}$ L and $Cellic^{(R)}$ CTec2 (1:1) was presented the highest yield of 10.67%. Finally, the 14.99% yield was obtained at 36 hr under the condition of 10% biomass and 30% enzyme mixture.

• Tribology and Lubricants
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• v.17 no.3
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• pp.171-178
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• 2001

In order to elucidate the lubricating mechanism of polyolester base oils [POEs], the wear characteristics of 27 kinds of polyolester base oils including mixed POEs were investigated. Their wear results were discussed in terms of the effect of molecular structure on wear performance and compared with those of mineral oil. In addition, the adsorption ability of POEs to reduced iron and their hydrolysis rates were measured and the effect of their molecular structures on the adsorptivity and hydrolysis rate of POEs was discussed, respectively. Finally, the lubricating mechanism anlyzed from these results of wear characteristics, adsorptivity and hydrolysis rate was proposed. That is to say, POEs are firstly adsorbed to friction surface and decomposed by hydrolysis or thermal degradation. Fatty acids obtained by degradation of POEs form adsorption film on friction surface. The larger become cohesive ability among fatty acid molecules in the adsorption film, the better gets the wear performance of POEs.

• Preventive Nutrition and Food Science
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• v.21 no.4
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• pp.338-347
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• 2016

The present study investigated the volatile compound, physicochemical, and antioxidant properties of beany flavor-removed soy protein isolate (SPI) hydrolyzates produced by combined high temperature pre-treatment and enzymatic hydrolysis. Without remarkable changes in amino acid composition, reductions of residual lipoxygenase activity and beany flavor-causing volatile compounds such as hexanol, hexanal, and pentanol in SPI were observed after combined heating and enzymatic treatments. The degree of hydrolysis, emulsion capacity and stability, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity, and superoxide radical scavenging activity of SPI were significantly increased, but the magnitudes of apparent viscosity, consistency index, and dynamic moduli (G', G") of SPI were significantly decreased after the combined heating and enzymatic treatments. Based on these results, it was suggested that the enzymatic hydrolysis in combination with high temperature pre-treatment may allow for the production of beany flavor-removed SPI hydrolyzates with superior emulsifying and antioxidant functionalities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.10
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• pp.1287-1293
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• 2008

This study investigated quality changes and functions of low-molecular soymilk according to hydrolysis time (30, 60, and 90 minutes). According to the results, pH of hydrolyzed groups were lower than that of the control group but it did not show a large difference according to hydrolysis time while sugar content was reduced with longer hydrolysis time. Although degree of hydrolysis and calcium tolerance increased with longer hydrolysis time, there was not a significant difference according to the time. Among free sugars, contents of glucose and fructose grew while those of sucrose and maltose tended to decline with time. Total free sugar content was the largest with 60 minutes of hydrolysis time recording 827.65 mg%. Total amino acid content was also the highest with hydrolyzed for 60 minutes recording 85.80 mg% and those of all hydrolyzed groups were higher than that of the control group. In addition, the content of essential amino acid increased significantly with time. In SDS-PAGE, checked for the tendency of becoming low molecules, molecular weights were found to be 33 kDa or less kDa in all hydrolyzed groups. When functional characteristics of soymilk such as electron donating, superoxide radical scavenging and ACE inhibitory activities were compared, longer hydrolysis time led to higher activities. From these results, overall quality of low molecular soymilk was superior when hydrolyzed for 60 minutes and the findings should be viable in the development of various types of functionally strengthened low-molecular soymilk in the future.

• Journal of the Korean GEO-environmental Society
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• v.13 no.9
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• pp.69-74
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• 2012

This study investigated the TNT decomposition by the treatment of alkaline hydrolysis. To obtain this objecitive, spectrum shift characteristics, pH effect, kinetics, and product analysis were examined during the alkaline hydrolysis by means of hydroxide ions. At pH = 12, an aqueous solution of TNT was changed into yellow-brown coloring, in which its absorbances were newly increased in a range of wavelength 400-600 nm. From the kinetic data, pseudo-first-order rate constant in a excess of hydroxide ion, in contrast to TNT concentration, was $0.0022min^{-1}$, which means that the reaction rate between TNT and hydroxide ion can be very slow, and that 1,047 min is necessary to achieve a 90% reduction of the initial TNT. In products analyses, nitrite ions and formic acid were mainly produced by the alkaline hydrolysis, nitrate ions and oxalic acid as minor products were generated.

• Journal of the Korean Chemical Society
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• v.36 no.3
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• pp.446-452
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• 1992

The rates of hydrolysis of aryl phenylacetates have been measured in the presence of piperidine in 80% acetonitrile-20% water(v/v). For the electron withdrawing substituents of leaving group, the hydrolysis is catalyzed by a general base and the Hammett $\rho_{LG}$ and Bronsted value $\beta$ are 5.28 and -2.72 at $30^{\circ}C$, respectively. These high senstivities of Hammett and Bronsted values are $E1_{C}B$ mechanism. But in the electron donating ones, the hydrolysis is catalyzed by a specific base and $B_{AC}2 mechanism is predominated. $pK_{SH}'s of phenylacetic acid ester and rate constants of hydrolysis $k_1$, $k_{-1)$, $k_2$ were calculated.

• KSBB Journal
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• v.10 no.5
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• pp.540-546
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• 1995

Dry corn gluten meal of 70% protein content was enzymatically hydrolyzed by alkaline protease in a pH-state reactor. Such process variables as temperature, pH, and enzyme-to-substrate ratio were varied, and at each condition degree of hydrolysis was monitored and calculated. The ultimate degree of hydrolysis, which ranged between 25 and 28% based on gluten protein mass, was not significantly affected by the process variables. However, $50^{\circ}C$ and pH 9-10 appeared optimum. Kinetic analysis indicated enzyme deactivation was negligible during the hydrolysis, and the experimental data were near perfectly fitted to the model kinetic equation which was modified after neglecting enzyme deactivation term. The enzyme reaction was 1$100\times$ scaled up and basically the same hydrolysis performance was resulted. Amino acid analysis showed the hydrolyzate was relatively rich in glutamine/glutamic acid, leucine, and alanine at 19.6, 16.1, and 12.3 mole %, respectively.

• Food Science and Preservation
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• v.4 no.3
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• pp.323-330
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• 1997

Changes in antioxidative substance levels in eleven different cultivars of persimmon leaves during growth were investigated. In general, the contents of soluble phenols, L-ascorbic acid and flavonoids in astringent persimmon leaves(APL) were higher than those of nonastringent persimmon leaves(NAPL). The soluble phenol contents in APL and NAPL showed a tendency to decrease throughout leaf growth. L-ascorbic acid content in APL decreased rapidly during growth, whereas its content in NAPL reached its highest value at the late of July, and then decreased rapidly. Major flavonoids in APL and NAPL were quercetin and Kaempferol which were present in conjugate forms. Before acid hydrolysis, the contents of kaempferol and quercetin in APL and NAPL remained at a relatively constant level until the late of July, and then decreased slightly. After acid hydrolysis, kaempferol contents in APL and NAPL varied significantly by cultivar and growth stage, while quercetin contents decreased slowly until the late of July, and then increased drastically, reached a maximum at the early of August, afterward continuously decreased. These results suggest that APL harvested at the early of June may be useful as potential sources of natural antioxidants.