Production of hemicellulosic sugars from Pinus pinaster wood by sequential steps of aqueous extraction and acid hydrolysis

Pinus pinaster wood samples were subjected to aqueous extraction at 130°C to remove extractives and to a sequential stage of hydrothermal processing under selected operational conditions to obtain hemicelluloses-free solids and liquors containing hemicelluloses-derived products (mainly oligomeric saccharides and monosaccharides). Liquors were separated from the media, supplemented with sulfuric acid (4%), and heated to cause the posthydrolysis of oligomeric saccharides to yield hemicellulosic sugars. The effects of the major operational conditions on the yields of the target products were assessed in selected experiments. The considered process enabled the recovery of hemicellulosic sugars (mannose, glucose, xylose, and galactose) at almost quantitative yields.     

Characterization of lignin-carbohydrate linkages in the residual lignins isolated from chemical pulps of spruce (<Emphasis Type="Italic">Picea abies</Emphasis>) and beech wood (<Emphasis Type="Italic">Fagus sylvatica</Emphasis>)

To investigate the linkage types between carbohydrates and lignin, residual lignins were isolated from three different unbleached pulps [kraft, alkaline sulfite anthraquinone methanol (ASAM), and soda with anthraquinone (AQ) and methanol] of spruce and beech wood and then characterized by oxidation with 2,3-Dichloro-5,6-dicyanobenzoquinone and followed by Prehm’s methylation. In residual lignins, sugar moieties were bound to lignins via benzyl ether bonds. In particular, galactose and mannose are predominantly linked to lignin fragments in residual lignins of spruce wood, while xylose and galactose are favored in the formation of LC bonds in the residual lignins of beech wood. In the case of hexoses, primary hydroxyl groups (C6 position) preferentially take part in benzyl ether linkages. Hydroxyl groups in the C2 and C3 positions of xylose participate in LC bonds and a small portion of arabinose was notably connected to lignin via the C5 position. Approximately seven or eight sugars were connected in soda/AQ/methanol residual lignin per 100 C9 lignin units, while the frequencies of LC bonds in kraft and ASAM residual lignins were distinctively less at one to three sugars per 100 C9 lignin units. The publication of this article was made possible by an Emachu Research Fund. The authors are grateful for the fund.     

Isolation, purification and some structural features of the mucilaginous exudate from Musa paradisiaca

The water-soluble polysaccharides isolated from the vascular gel of Musa paradisiaca, were fractionated via anion exchange chromatography into four fractions. Fractionated polymers contained arabinose, xylose and galacturonic acid as major sugars, together with traces of galactose, rhamnose, mannose and glucose residues. Methylation analysis revealed the presence of a highly branched arabinoxylan with a significant amount of terminal arabinopyranosyl units and an arabinogalactan type I pectin. Periodate oxidation studies supported the results of methylation analysis.     

Polysaccharides in cones of eleven coniferous species growing in Turkey

Composition of polysaccharides in the cones of conifer species growing in Turkey was studied. The content of polysaccharides was between 39 and 57% (w/w). The total amount of polysaccharides was generally higher in pine species. Polyoses were the predominant polysaccharides. The percentage of polyoses was between 23.3 and 33.9% (w/w). The main units of polyoses were mannose and galactose, while in some species xylose was the other important sugar unit. Between 1 and 6.7% of the polyoses were soluble in hot water. Polyoses were more readily dissolved from fir species than from other species. Galactoglucomannan was dissolved from all cones. Contrary to wood, the content of cellulose was only between 13 and 27.5% (w/w) in cones.     

Chemistry and ecotoxicity of heat-treated pine wood extractives

Pine (Pinus pinaster) wood was heat-treated in an autoclave for 2?C12?h at 190?C210°C. Hemicelluloses were the first compounds affected by the treatment. In general, the sugar decrease was higher for arabinose and galactose followed by xylose and mannose. Lignin started to degrade for small mass losses but at a slower rate than hemicelluloses, and cellulose only degraded significantly for severe treatments. Almost all of the original extractives disappeared, and new compounds arose such as anhydrosugars and phenolic compounds. The compounds that might leach from heat-treated wood were mainly those identified in the water and ethanol extracts, all of which were not harmful at the existing concentrations, thereby reinforcing the wood heat treatment as an environmental benign process.     

灵芝多糖体的提取及其理化性质的研究

灵芝是一种木材腐朽菌,具有良好的药用价值,在中国和其它一些国家享有盛誉。作者对赤(灵)芝(Ganoderma lucidum)子实体多糖的提取及其理化性质进行了研究。结果表明,粗多糖得率为1.38％,纯化后的糖经薄层色谱和气相色谱分析查明含有木糖、甘露糖、阿拉伯糖、半乳糖和葡萄糖,糖基比依次为1:1:1.7:5:20。用凝胶过滤得分于量约为23000和34000。经红外光谱测定该多糖在1050、1140、1420和3400cm~(-1)处均有明显的吸收峰。本文提出了一个从灵芝子实体分离和纯化多糖体的方法。     

Chemical composition of earlywood and latewood in Norway spruce heartwood,sapwood and transition zone wood

This study focused on the distribution of wood components along a cross section of a spruce stem. Thin samples of earlywood and latewood were analysed by special micro-scale analytical techniques. Heartwood contained significantly more lignin and less cellulose than sapwood. The total content of hemicelluloses was the same along the radial direction, but the distribution of sugar units differed. The amounts of arabinoglucuronoxylan and pectins were larger in the heartwood. The transition zone between heartwood and sapwood had a specific composition, with less lignin and lipophilic extractives than heartwood and sapwood. For earlywood and latewood, significant differences were found in the distribution of sugar units in hemicelluloses. Latewood contained clearly more galactoglucomannan than earlywood, and conversely less pectins. The lipophilic extractives were also less concentrated in the latewood.Abbreviations EW or E earlywood - LW or L latewood - HW heartwood - SW sapwood - TZ transition zone wood - A.R. annual ring - AcBr Acetyl bromide - Ara arabinose - Xyl xylose - Gal galactose - Glc glucose - Man mannose - Rha rhamnose - GlcA glucuronic acid - MGlcA 4-O-methyl-glucuronic acid - GalA galacturonic acid - o.d. oven dry     

高温热处理对桃花心木化学性质的影响

热处理是木材加工行业中常用的处理手段之一,可有效提升木材尺寸稳定性及具有防生物侵蚀能力,但在一定程度上也会降低木材的力学性能.热处理导致木材材性变化的根本原因是木材组分含量及其分子结构在热量作用下发生了变化.笔者探索了不同热处理温度下(150,165,180,195和210℃)桃花心木材的化学组分变化.结果表明:经热处...     

The pharmacological activity of wheat bran polysaccharides

(Glucurono)arabinoxylans were extracted from the wheat bran with acetate buffer in the first step (WBH1) and with dilute alkali in the second step (WBH2). In both samples xylose and arabinose dominated, accompanied with smaller amounts of galactose, glucose, mannose and uronic acids mainly in WBH1. WBH1 was free of protein and with low content of phenolic compounds. Fraction WBH2 contained relatively low levels of proteins and about 4.5% of the total phenolic. When tested for antitussive activity, the (glucurono)arabinoxylans exhibited comparable cough-suppressing effect with centrally acting codeine. The observed effects of bronchoconstriction are limiting practical application of WBH2.     

向日葵盘及其果胶主要组成的研究

研究结果表明，向日葵盘组成复杂，初步测定出１０多种天然化合物，其果胶含量以海绵状肉质部位最高，锯齿形苞片部位最低。用气相色谱法分别测定了向日葵盘及其果胶中各种糖基的相对含量，发现它们都含有木糖、阿拉伯糖、甘露糖、半乳糖和葡萄糖等，向日葵盘中葡萄糖含量最高果胶中含半乳糖最多。向日葵盘用水预洗得到的水溶性果胶，其酯化度大于５０％，属于高酯果胶，其表观分子量为１７３４００，向日葵盘经一分别用稀无机酸及多     

Structural, histochemical and chemical characterization of normal, tension and opposite wood of Subabul (Leucaena leucocephala (lam.) De wit.)

Structure, histochemistry and chemical composition of tension (TW), opposite (OW) and normal wood (NW) of Leucaena leucocephala have been studied using histological, histochemical and biochemical methods. TW vessels are longer and have a larger diameter than NW vessels, and the rays are shorter and thinner. The G-layer replaced S3 and parts of S2 wall layers in TW fibres. TW further contained less lignin that also had a lower syringyl-to-guaiacyl ratio. The lignin was also more condensed. The content of α-cellulose was high in TW. TW contains hemicelluloses and pectins composed of more galactose, and less xylose, mannose, 4-O-methylglucuronic acid and galacturonic acid compared to that of OW. This study suggests that in the TW of Leucaena, the amount and composition of lignin, hemicelluloses and pectins differ considerably from that in OW and NW.     

Molecular properties of lignin-carbohydrate complexes from beech (Fagus crenata) and pine (Pinus densiflora) woods

Summary Lignin-carbohydrate complexes (LCC) were isolated from pine (Pinus densiflora) and beech (Fagus crenata) milled-wood lignins. The LCCs were treated with enzyme to obtain precipitates (A-P, B-P) and water soluble fractions. The water soluble fraction from beech LCC was subjected to gel filtration to give LCC fragments (B-E-I). In order to protect the phenolic hydroxyl group, B-E-I and B-P were methylated with diazomethane, resulting in nonphenolic LCC fractions B-E-Ip and B-Pp, respectively. On treatment of B-E-I and B-P with sodium hydroxide, a remarkable amount of xylose and a trace of arabinose were detected as monomeric sugars. However, the same alkaline treatment of B-E-Ip and B-Pp gave only a faint trace of xylose. With DDQ treatment of acetylated B-E-I and B-P, monomeric sugars were released in the same amount as those obtained on alkaline treatment. Methylation of the monomeric sugars gave monomethylated xylose. From these results, it was concluded that xylose residues participate in lignin-carbohydrate linkages, and that lignin is linked to xylose at the 0–2 or 0–3 positions through an alkali-labile benzyl ether bond. The molecular-weight distributions of the lignin moieties, measured by HPLC, indicate that the lignin moieties of beech LCC are 100 times larger but less frequent than those of pine LCC. This nonuniformity of distribution of lignin and carbohydrate moieties in hardwood LCC molecules would result in less hydrophobic interaction in aqueous solutions.     

Seasonal fluctuations of low‐molecular‐weight sugars,starch and nitrogen in sapwood of Pinus sylvestris L.

The content of water‐soluble substances and starch in the living tree stem at the time of felling influences wood durability during further utilization. The aim of the study was to describe the annual and seasonal fluctuations in the contents of stored carbohydrates and nitrogenous compounds. The contents of soluble sugars, starch, and nitrogen were measured in the outer sapwood (0–15 mm from cambium) of 65‐yr‐old Scots pine {Pinus sylvestris L.) trees during an annual cycle. To study the influence of growth conditions, samples were taken from different stands in Sweden, in one stand from a control and a fertilized block. The effect of the age of the trees on the content of stored substances was also considered by comparing young (10–15 yrs old) and older trees (40–65 yrs old). Determination of the carbohydrates was carried out using enzymatic analysis. The outer pine sapwood contained a higher content of low‐molecular weight sugars during autumn and winter than during spring and summer. Starch content rose at the beginning of the growth period and decreased in autumn. The content of soluble sugars increased towards the cambium on all sampling occasions. Fructose and glucose were dominant sugars in all the stands studied. Seasonal changes of sucrose were different from those of glucose and fructose, in that the sucrose content was already decreasing in February. The variations in the nitrogen content of the sapwood were far smaller than those of the soluble sugars. No significant differences were found between the stands with regard to glucose, fructose and the sum of all three sugars. The fertilized block showed low content of sucrose and nitrogen. It is concluded that seasonal fluctuations are more important with regard to the sugar content than the effect of growth conditions. Data indicate a lower content of soluble sugars and nitrogen in the outermost sapwood of young trees as compared with older trees.     

马尾松苗木小分子有机化合物动态监测

对马尾松1、2年生苗木中松醇、肌醇、可溶性糖等小分子有机化合物进行动态监测。结果表明:1年生马尾松苗木针叶内松醇含量随着苗木的生长而逐渐增加,并在木质化期达到最高;2年生苗木针叶内松醇含量随着苗木生长反而下降,只在木质化期有所增加。肌醇、半乳糖和麦芽糖含量的变化较为复杂,均没有规律性。葡萄糖含量的变化比较平稳,2年生苗木在8月份时其葡萄糖含量明显高于1年生苗木的。     

日本落叶松木材的化学组成研究

对不同树龄和不同部位日本落叶松木材的化学组成、糖类组成进行了研究。结果表明,不同树龄日本落叶松木材的化学组成存在一定的差异：随着树龄的增大,总碳水化合物含量逐渐降低;冷水抽出物、热水抽出物和1％NaOH抽出物的含量增加;灰分含量逐渐降低;聚糖组成中葡萄糖和木糖含量降低,半乳糖含量增加。从化学组成分析看,12年生和15年生日本落叶松的木材比20a以上树龄的更适合用作造纸原料。与兴安落叶松相比,日本落叶松的水抽出物与1％NaOH抽出物含量较低,聚糖中葡萄糖含量较多而半乳糖含量较少;从化学组成来说,日本落叶松木材是一种优于兴安落叶松木材的造纸原料。     

Cellular structure and chemical composition of cork from the Chinese cork oak (Quercus variabilis)

Quercus variabilis Blume, the Chinese cork oak, is an oak species with a thick cork outer bark. The cork is exploited at a limited scale in China and considered of lower quality than the commercial cork from Quercus suber. We studied an industrial cork granulate feedstock of Q. variabilis in relation to cellular structure and chemical composition and compared it to Q. suber cork under a material’s perspective. The cork of Q.variabilis has 1.1 % ash, 9.6 % extractives, 34.8 % suberin and 19.1 % lignin. The monosaccharide composition with shows a predominance of hemicelluloses: glucose 42.8 % of total neutral sugars, xylose 27.5 %, arabinose 15.4 %, galactose 9.0 %, mannose 4.0 %, rhamnose 1.2 %. The FT-IR spectrum shows the indicative peaks of suberin. The composition is overall similar to that of Q. suber cork. Q. variabilis cork has the typical cellular characteristics of bark cork tissues with a regular and radially aligned structure of cells without intercellular voids. Solid volume fraction was estimated at approximately 16 %. Compared with Q. suber, the Q. variabilis cork cells are smaller, the cell wall undulation and the overall row alignment less homogeneous, the cell surface is irregular and the solid volume proportion higher. The characteristics of Q. variabilis cork support its use as a cellular material for sealing, insulation and energy absorption, but the overall quality is lower than that of Q. suber cork. The negative impact of the higher density and structural lower uniformity at tissue and cell level should be evaluated for processing and product performance.     

Investigation of Carbohydrate Compositions for Poplar I-214 and Chinese Fir

Carbohydrates are main compositions for wood (Menachem et al. 1991). The chemical components of poplar I-214 and Chinese fir have been reported (Huang Luohua et al. 2002; Qin Tefu et al. 2003). Through the studies of carbohydrate compositions of poplar I-214 and Chinese fir, different composition of monosaccharides can be found in both poplar I-214 and Chinese fir. 1 MATERIALS AND METHODS 1.1 Materials Wood samples of Chinese fir (Cunninghamia lancedata) and poplar I-214 (Populus…     

Distribution of boron in wood treated with aqueous and methanolic boric acid solutions

The distributions of boron in Japanese cedar (Cryptomeria japonica D. Don) sapwood blocks treated with aqueous or methanolic boric acid [B(OH)₃] solutions were explored through Raman spectroscopy and prompt gamma-ray analysis (PGA). B(OH)₃ was the sole boron species observed in Raman spectra of the wood blocks treated with either solution. Plots of weight gain of the treated wood blocks versus boron concentration in treatment solutions were found to be linear. The results indicated that the methanolic solution makes it possible to impregnate wood with much larger amounts of boron than the aqueous solution. PGA confirmed that B(OH)₃ was highly enriched near the end grains of the treated wood blocks. Raman measurements suggested that boron content in the bulk of the wood block is not as large as expected from the weight gain of the treated wood blocks when an ordinary air-drying method is used. It was concluded that the aqueous solution impregnates the cell walls of wood with boron more easily than the methanolic solution. Part of this report was presented at the 55th (Kyoto, March 2005) and 56th (Akita, August 2006) Annual Meetings of the Japan Wood Research Society. This article follows the previous rapid communication “Analysis of boron in wood treated with boric acid solutions using Doppler broadening method of prompt gamma-rays.” J Wood Sci (2006) 52:279–281     

Composition and proposed structure of a water-soluble glycan from the Keumsa Sangwhang Mushroom (Phellinus linteus)

Phellinus linteus is a mushroom which has been prized in Korea for its medicinal properties since ancient times. A glycan preparation from this source has shown promise in experimental anti-tumour and metastasis studies, but the glycan has not been well characterized. In the present work, the glycan fraction of a hot water extract from P. linteus (Keumsa Sangwhang Mushroom, Korea) has been isolated following ammonium sulfate precipitation, dialysis/concentration and anion exchange chromatographic steps. Analyses for monosaccharide composition showed glucose and mannose to be the major constituents. Digestion of the glycan fraction with specific glycosidases and by linkage analysis allowed us to propose a core beta(1-3) linked glucan heavily substituted via (1-6) links with beta(1-3) linked mannose chains. Significant levels of galactose and xylose, present in the glycan fraction, may be associated with this glucomannan or not. These findings are consistent with the view that a core beta(1-3)-linked glucan chain with beta(1-6) branch points is a common feature of mushroom glycans possessing anti-tumour activity.     

Characteristics of normal and discoloured wood of Ilomba (Pycnanthus angolensis Exell)

Summary In the West African Ilomba wood (Pycnanthus angolensis Exell) discolourations frequently develop after felling, which lead to serious degradation with regard to utilization. Therefore, structure and chemical composition of normal and discoloured wood were investigated in order to characterize the original wood and give a detailed account of the reactions which lead to discolourations. According to the results Ilomba, in normal condition, is all sapwood, which explains its high reactivity. The species does not have the ability to develop heartwood; only false heartwood is formed, initiated by exogenous influences. Discolourations arising in the wood after felling are reddish-brown, due to the deposition of extraneous compounds in the lumina of the ray cells. Soluble sugars disappear and the permeability decreases as a result of tyloses development. From discoloured wood only 60% of extraneous compounds could be extracted as compared to the normal sapwood, thus indicating that polymerisation of extraneous compounds takes place. Discoloured wood appears even more susceptible to decay than the bright sapwood. The pH-value increases from about 5.5 to 7.5 during discolouration, and bacteria present within the reddish-brown zones are involved in that process.We are indebted to Mrs. R. Endeward for assistance in the experimental work, to Prof. N. Parameswaran for support in the REM work, to Fa. Bernhard, Wangen and to Mr. K.-G. Dahms, Hamburg, for the supply of Ilomba wood. Acknowledgement is given to Deutsche Forschungsgemeinschaft for financial support