• 펄프종이기술
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• 제46권6호
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• pp.1-7
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• 2014

Dissolving part of xylan and lignin in lignocellulosic biomass by base can be used as pretreatment technique. Cork oak was pretreated with sodium hydroxide solution and the pretreatment effects were evaluated with two critical factors - NaOH concentration and pretreatment temperature. Some of xylan and lignin were removed by base pretreatment. At $90^{\circ}C$ and 13% NaOH pretreatment, 22.0% of lignin and 78.8% of xylan removed by base treatment. Enzymatic hydrolysis of cork oak which was pretreated at higher temperature or concentration was further improved. After pretreatment of cork oak with 13% NaOH at $90^{\circ}C$, the conversion rate of cellulose to fermentable sugars were reached up to 91.3%. At ethanol fermentation with enzymatic hydrolysate from different pretreatment conditions, all enzymatic saccharification liquids were well fermented by Saccharomyces cerevisiae.

• KSBB Journal
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• 제4권3호
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• pp.235-240
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• 1989

본 연구에서는 매년 700여만톤 생산되는 볏짚을 자원화 하기 위하여 암모니아-냉동-파열법 (AFEX)을 사용하였다. AFEX으로 전처리된 볏짚은 처리되지 않은 것보다 대랴 4배 이상의 가수분해율을 얻을 수 있었다. 또한 어떼한 전처리 방법보다도 처리하는 과정이 쉽고 당화율도 90%로 이상이며, 경제성이 높다.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4377-4381
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• 2011

In this study, real-time and label-free methods for monitoring the enzymatic reaction of urease, which releases ammonia through the hydrolysis of urea in an aqueous solution, were developed using a liquid crystal (LC)-based pH sensor. Nematic liquid crystal 4-cyano-4'-pentylbiphenyl (5CB), doped with 4'-pentyl-biphenyl-4-carboxylic acid (PBA), exhibited a shift in optical appearance from bright to dark when it was in contact with ammonia generated from the enzymatic reaction between urease and urea. This optical change was attributed to the anchoring transitions of LCs caused by hydrophobic interactions between the tails of deprotonted PBA ($PBA^-$) molecules and the LCs at the aqueous/LC interface. This novel technique holds great promise for the sensitive detection of urease along with its substrates and inhibitors.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.74-76
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• 2008

Autohydrolysis at different temperature levels was applied as industrial hemp pretreatment technique for glucose generation. Main structural components removed by autohydrolysis was xylan, which is more sensitive in acidic hydrolysis condition than cellulose or lignin. Higher temperature reaction conditions promoted more biomass components (xylan) removal than lower temperature, which led to better respond to enzymatic saccharification of residual biomass after autohydrolysis. With $185^{\circ}C$ and 60 min, saccharification degree was 53.0% of cellulose in hemp woody core biomass.

• 접착 및 계면
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• 제7권2호
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• pp.19-25
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• 2006

미생물 합성 고분자인 poly(hydroxylalkanoate)s (PHAs)의 초기효소분해는 표면침식의 메커니즘으로 진행하므로 이들의 분해거동은 표면특성을 개질로서 조절할 수 있다. 본 연구에서는 효소분해속도를 조절하기 위하여 플라즈마 기법을 PHAs 표면특성의 개질에 적용하였다. $CF_3H$와 $O_2$ 플라즈마를 사용하여 재료 표면에 각각 소수성 및 친수성을 부여하였다. 효소분해 실험은 pH 7.4의 0.1 M potassium phosphate 완충용액에서 Alcaligenes facalis T1에서 정제된 poly(hydroxybutyrate) 분해효소를 첨가하여 행하였다. $CF_3H$ 플라즈마 처리된 시편의 경우 표면 층의 불소화에 따른 소수성의 증가와 분해 효소에 대한 비활성으로 초기분해 속도가 상당히 지연됨을 관찰하였으나 $O_2$ 플라즈마 처리에 의한 표면 친수성은 분해속도의 촉진 등에 큰 영향을 미치지 않았다.

• Journal of Ginseng Research
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• 제44권1호
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• pp.44-49
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• 2020

Background: Salting-out extraction (SOE) had been developed as a special branch of aqueous two-phase system recently. So far as we know, few reports involved in extracting ginsenosides with SOE because of the lower recovery caused by the unique solubility and surface activity of ginsenosides. A new SOE method for rapid pretreatment of ginsenosides from the enzymatic hydrolysates of Panax quinquefolium was established in this article. Methods: The SOE system comprising ethanol and sodium carbonate was selected to extract ginsenosides from the enzymatic hydrolysates of Panax quinquefolium, and HPLC was applied to analyze the ginsenosides. Results: The optimized extraction conditions were as follows: the aqueous two-phase extraction system comprising ethanol, sodium carbonate, ethanol concentration of 41.51%, and the mass percent of sodium carbonate of 7.9% in the extraction system under the experimental condition. Extraction time had minor influence on extraction efficiency of ginsenosides. The results also showed that the extraction efficiencies of three ginsenosides were all more than 90.0% only in a single step. Conclusion: The proposed method had been successfully applied to determine ginsenosides in enzymatic hydrolysate and demonstrated as a powerful technique for separating and purifying ginsenosides in complex samples.

• Journal of Pharmaceutical Investigation
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• 제21권2호
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• pp.67-71
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• 1991

A simple and sensitive method was developed for the quantification of free and conjugated bile acids in bezoar without prior hydrolysis. $3{\alpha}-Hydroxy$ bile acids are first oxidized to 3-keto bile acids in the reaction catalyzed by $3{\alpha}-hydroxysteroid$ $dehydrogenase(3{\alpha}-HSD)$. During this oxidative reaction, an equimolar quantity of nicotinamide adenine dinucleotide(NAD) is reduced to NADH and subsequently oxidized to NAD with concomitant reduction of nitrotetrazolium blue(NTB) to diformazan by the catalytic action of diaphorase. The diformazan has an absorbance maximum at 540 nm. The intensity of the color produced is directly proportional to bile acids concentration in the bezoar extracts. The optimum conditions for the enzymatic reaction such as effects of reaction time, reaction temperature and pH, and stability were investigated. Calibration plots for the sodium chelate observed to be linear and intra-, inter-assay analytical recovery of bile acids averaged $97.65{\pm}3.4%(S.D.)$. Therefore, it is considered that the quality control of total bile acids from bezoar or bezoar-containing liquid preparation using this simple and sensitive assay system will be acceptable. Also current bezoars and bezoar-containing liauid preparations were examined their total bile acids from this method.

• Journal of Microbiology and Biotechnology
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• 제13권5호
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• pp.773-777
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• 2003

The color of Congo red hinders the spectrometric measurements of a concentration of hydrogen peroxide and enzyme activity (Horseradish peroxidase; HRP) during enzymatic decoloring of Congo red. In this study, a method was developed to measure peroxidase activity and hydrogen peroxide concentration in the presence of Congo red. The oxidation product of HRP/hydrogen peroxide and ABTS(2,2'-azino-bis-(3-ethylbenzotriazoline-6-sulfonic acid)) formed a dark green color. The spectrum of this product showed absorption bands at 420 nm and 734 nm. When compared with the Congo red spectrum, the absorption at 734 nm of this product did not overlap with Congo red, thus making the hydrogen peroxide measurement possible even in the presence of Congo red. Kinetic study of decoloring of Congo red performed by this method showed that the decoloring reaction followed the Michaelis-Menten kinetics. Pulse feeding of hydrogen peroxide, upon depletion, significantly increased the decoloring of Congo red. This result shows that this newly developed technique can monitor, predict, and improve the enzymatic decoloring process.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.111-122
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• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• Journal of the Korean Wood Science and Technology
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• 제45권2호
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• pp.232-242
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• 2017

The objective of this study was to examine changes in the porosity and internal structure of wood as it goes through the process of saccharification (extraction of fermentable sugars). This study also examined the use of different drying methods to prepare samples for characterization of internal pores, with particular emphasis on the partially disrupted cell wall. Aspen wood flour samples after dilute acid pretreatment followed by enzymatic hydrolysis were examined for nitrogen adsorption. The resulting isotherms were analyzed for surface area, pore size distribution, and total pore volume. Results showed that freeze drying (with sample pre-freezing) maintains the cell wall structure, allowing for examination of saccharification effects. Acid pretreatment (hemicellulose removal) doubled the surface area and tripled the total volume of pores, which were mostly 10-20 nm wide. Subsequent enzymatic hydrolysis (cellulose removal) caused a 5-fold increase in the surface area and a ~ 11-fold increase in the total volume of pores, which ranged from 5 to 100 nm in width. These results indicate that nitrogen adsorption analysis is a feasible technique to examine the internal pore structure of lignocellulosic residues after saccharification. The information on the pore structure will be useful when considering value-adding options for utilizing the solid waste for biofuel production.