• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Pre-symposium of the 10th ISWPC Recent Advances in Paper Science and Technology
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• pp.254-258
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• 1999

The distribution of anionic groups in the fibers, the fines, the colloidal fraction and the dissolved fraction, respectively, of thermomechanical pulp (TMP) suspensions was determined and peroxide bleaching of spruce TMP were also studied. Spruce TMP was extracted with hexane, treated with alkali, or bleached with peroxide. Suspensions made at pH 5.5 were fractionated into long fibres, large fines, small fines, a colloidal fraction and a dissolved fraction. The charge of the fractions was determined using polyelectrolyte titration. To determined the origin of the charges, the contents of fatty acids, resin acids and acidic units in hemicelluloses in the different fractions were determined by has chromatography. Extraction of TMP with hexane prior to fractionation increased the measured charge of the fibres. The removal of the wood resin probably uncovered some carboxyl groups on the fibre surfaces, or improved th e penetration of polybrene into the pores of the fibres. The charge of the fines and the colloidal fraction was lower when the wood resin had been removed. Alkaline treatment of the TMP increased the charge of the fibres and fines, mainly because of demethylation of pectins. Alkaline treatment increased the charge also of the dissolved fraction, because of the release the charge also of the dissolved fraction, because of the release of pectic acids into the water phase. Alkaline peroxide bleaching further increased the charge of fibres and the dissolved fraction, most likely because of lignin oxidation. The charge of the colloidal fraction, consisting mainly of wood resin, was only slightly affected by alkaline treatment and peroxide bleaching. The anionic groups in TMP suspensions were mainly free uronic acids in the hemicelluloses. The contribution from the fatty and resin acids was substantial only for the colloidal fraction.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.15-22
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• 1997

The effectiveness of presteaming for improving CCA treatability on refractory Japanese larch heartwood was investigated in this study. Presteaming was effective on improving treatability, and the extent of improvement was dependent on moisture contents of wood specimen and steaming conditions. Green wood showed higher average value in both preservative retention and penetration than dry wood, and steaming under pressure conditions also had higher treatability than steaming at atmospheric conditions. The degree of improvement for treatability was increased with the extension of steaming period. Treatability of dry wood pres teamed under pressure conditions more than 6 hours and green wood for 3 hours was similar to that enhanced by conventional incising. Presteaming green wood under pressure conditions more than 6 hours was more effective than conventional incising in improvement of CCA treatability, and resultant treatability satisfied a minimum value required for CCA-treated wood for being used at the regions of hazard class H3 and H4. In addition, an improvement of treatability by presteaming was due to an increase in permeability resulted from the degradation of hemicelluloses within aspirated pit membrane and cell wall, not the removal of extractives from pit membrane. The reduction in strength, measured as longitudinal compressive strength, due to pres teaming was related with the degradation of hemicelluloses, and was increased as steaming conditions were severe. The degree of strength reduction associated with presteaming treatment to obtain required treatability could be quantified from the relatively good relation between the increase in treatability and the decrease in strength.

• 한국식품영양과학회지
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• 제25권4호
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• pp.715-719
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• 1996

Dietary fibers consist mostly of complex carbohydrates such as cellulose, hemicelluloses and pectins, and also included are carbohydrate-based gums or hydrocolloids exampled as alginate, carrageenan, galactomannan xanthan, etc. Due to structural diversity, dietary fibers can be classified by various ways i.e., source, plant function, solubility, charge and topology. Understanding on the plant cell wall structure is of primary importance, since physicochemical properties of dietary fibers are dependent on the existence patterns in the cell wall. Depending on the four distinct observational dimensions, the physical parameters of dietary fibers were discussed in terms of raw sources, bulky & complex plant cell wall materials, individually separated hydrocolloid materials and specifically designed materials. Each existence state possesses the distinct physical parameters governing a variety of physiological properties of dietary fibers.

• Journal of the Korean Wood Science and Technology
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• 제23권4호
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• pp.54-59
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• 1995

This experiment was carried out to evaluate the role of oxalic acid metabolism in the incipient decay of brown rotting, and to investigate the effects of various compositions of culture medium. Until 5days incubation, the amount of oxalic acid produced by Tyromyces palustris was increased, while pH was gradually decreased. The difference in oxalic acid production depending on carbon sources was not significant and the pH adjustment of media did not stimulate the production of oxalic acid. In this experiment, hemicellulose was hydrolyzed with 1% oxalic acid, so it is suggested that nonenzymatic acid hydrolysis of hemicelluloses might be involved in the process of incipient decay of brown-rot fungi.

• Journal of Plant Biology
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• 제29권4호
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• pp.263-284
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• 1986

Effects of putrescine, spermidine and spermine on the activity of D-glucose-6-phosphate cyclohydrolase in the Daucus carota L. protoplast cultured for 4 days and effects of polyamines on the incorporation of D-[u-14C]-glucose treated to protoplasts in culture-medium were investigated. The activity of D-glucose-6-phosphate cyclohydrolase was increased by polyamines and among them spermine was the most effective. Polyamiens increased protein synthesis and this due to the increasing effect of the polyamines on the synthesis of glycoprotein which is one of cell wall components. The synthesis of cell polysaccharides, such sa pectic substances, hemicelluloses and cellulose was increased by polyamines, which stimulated synthesis of pectin substances, and hemicellulose more greatly than that of cellulose, and spermidine was the most effective. In the light of the above results it seems that the polyamines increase cell wall regeneration by the stimulation of enzyme activities which synthesize cell wall components.

• 한국자원식물학회지
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• 제21권3호
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• pp.222-225
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• 2008

Chemical composition and enzymatic saccharification characteristics of hemp woody core were investigated by their chemical composition analysis and enzymatic saccharification with commercially available cellulases (Celluclast 1.5L and Novozym 342). Hemp woody core have higher xylan and lower lignin contents than its bast fiber. Based on hemicelluloses and lignin composition, hemp woody core is similar with hardwood biomass. However, cellulose was more easily converted to glucose than xylan to xylose and this trend was confirmed both hemp woody core and yellow poplar. Hemp woody core biomass shows higher saccharification than yellow poplar (hardwood biomass) based on cellulose and xylan hydrolysis. With easier enzymatic saccharification in cellulose and xylan, and similar chemical composition, hemp woody core have better biorefinery feedstock characteristics than hardwood biomass.

• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.663-671
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• 2022

The saccharification of cellulose and hemicellulose is essential for utilizing lignocellulosic biomass as a biofuel. While cellulose is composed of glucose only, hemicelluloses are composed of diverse sugars such as xylose, arabinose, glucose, and galactose. Sulfolobus acidocaldarius is a good potential candidate for biofuel production using hemicellulose as this archaeon simultaneously utilizes various sugars. However, S. acidocaldarius has to be manipulated because the enzyme that breaks down hemicellulose is not present in this species. Here, we engineered S. acidocaldarius to utilize xylan as a carbon source by introducing xylanase and β-xylosidase. Heterologous expression of β-xylosidase enhanced the organism's degradability and utilization of xylooligosaccharides (XOS), but the mutant still failed to grow when xylan was provided as a carbon source. S. acidocaldarius exhibited the ability to degrade xylan into XOS when xylanase was introduced, but no further degradation proceeded after this sole reaction. Following cell growth and enzyme reaction, S. acidocaldarius successfully utilized xylan in the synergy between xylanase and β-xylosidase.

• 한국식품저장유통학회지
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• 제15권4호
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• pp.532-541
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• 2008

미강 식이섬유인 헤미셀룰로오스를 효율적으로 추출할 수 있는 공정을 개발하고자 반응표면분석법에 의한 헤미셀룰로오스 추출공정 최적화를 실시하였다. 중심합성계획에 따라 NaOH 농도($X_1$), 추출 시간($X_2$)을 독립변수($X_i$)로 하고 추출물의 특성 즉, 추출 수율($Y_1$), Xyl/Ara ratio($Y_2$), 우론산($Y_3$), 베타 글루칸($Y_4$), 총 당($Y_5$)을 종속변수로 하여 추출을 실시하였다. 그 결과, R-square는 $0.8626{\sim}0.9319$으로 나타났으며, 추출 수율은 NaOH 농도가 증가하고 추출 시간이 증가함에 따라 값이 증가하였다. 추출 수율을 고려하여 이들 추출물의 특성을 모두 만족시키는 최적 추출조건은 NaOH 농도 2.45 M, 추출 시간 24.2 시간으로 나타났으며 예측된 최적 추출조건에서 실험한 결과, 각 종속변수들의 예측값과 실제값이 유사하게 나타났다. 최적 추출물의 구조적 특성을 조사한 결과, 표면구조는 매우 불규칙한 망상구조의 형태로 작은 입자와 큰 고분자 입자가 함께 관찰되었으며 평균 분자량은 $235{\sim}240$ kDa과 $8.0{\sim}9.4$ kDa의 범위로 나타났다.

• Korean Chemical Engineering Research
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• 제51권5호
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• pp.561-567
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• 2013

본 연구에서는 바이오연료 생산을 위한 헤미셀룰로오스의 회수 목적으로 혼합 하드우드 칩을 크라프트(kraft) 펄핑공정 전에 녹액(green liquor)으로 선-펄핑추출(pre-pulping extraction) 하였다. 본 실험에 사용된 녹액은 황화나트륨과 탄산나트륨이 주요 성분이며, 이 녹액에 목재 건조 질량당 0, 1, 3, 5%의 알칼리($Na_2O$)를 각각 충진하였다. 가혹 조건에 따른 선-펄핑추출액의 구성 성분을 알아보기 위해 추출은 반응시간은 1~2 h로 달리하면서 $160^{\circ}C$ 조건에서 실험을 수행하였다. 선-펄핑추출공정은 헤미셀룰로오스 추출시간과 녹액 주입 정도의 가혹도(severity)에 따라서 하향류 공정(downstream process)에서 활용 가능한 아세트산(acetic acid)과 단당류 농도, 그리고 유기산과 퓨란(furan)과 같은 분해 생성물의 축적 정도가 변한다. 본 연구 결과에서는 알칼리 주입 양이 증가할수록 헤미셀룰로오스에 존재하는 아세테이트(acetate)의 곁사슬과 용해성 및 리그닌의 양은 증가하지만, 추출액에서 탄수화물과 당류는 상당히 감소하였다. 특히 고온수(hot water)로 추출(알칼리 주입 0%)하는 경우 29.80 g/L 이상의 가장 많은 양의 탄수화물이 추출되었으나, 펄프 수율은 가장 많이 감소하였다. 또한 3% 녹액의 추출은 펄프 수율은 증가하였으나 당은 7.08 g/L로 많은 양이 감소하였다. 이 논문에서 얻어진 데이터를 통해 크라프트 펄핑공정에 추출공정 통합을 위한 헤미셀룰로오스 추출 조건을 최적화할 수 있을 것이다.

• 펄프종이기술
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• 제46권1호
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• pp.29-38
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• 2014

Guar gum is added to the pulp suspension at the suction side of the fan pump just before the sheet is formed on either a fourdrinier or cylinder machine. Guar gum replaced and supplements these hemicelluloses in paper bonding with many advantages, which include improved sheet formation with a more random distribution of pulp fibers. But, guar gum has serious storage problem. This material has easily decayed after High-temperature conditions such as summer. In this study, various properties of cotton handsheet were measured to solve the problem of deformation while storing guar gum and to improve the durability. After aging, which is one of the durability tests, cotton handsheet with 0.2% and 0.3% of A-PAM showed improved mechanical properties and bursting index and folding endurance of cotton handsheet with 0.3% of A-PAM were similar to those with guar gum. The yellowness loss of cotton handsheet with synthetic polymers was lower than those with guar gum.