Of wheat-straw hemicellulose

Fig. 5 FTIR spectra of commercial xylan from birch wood (line 1) and FTIR spectra of wheat straw hemicellulose extracted with 0.25 mol/1 NaOH/30 °C (tine 2), 0.50 mol/1 NaOH/30 °C (line 3), 0.25 mol/ 1 NaOH/55 °C (line 4), and 0.50 mol/1 NaOH/55 °C (line 5) all the treatments for 2 h...

Sun, Runcang Sun, X. F. Bing, X. Succinoylation of Wheat Straw Hemicelluloses with a Low Degree of Substitution in Aqueous Systems. J. Appl Polym. Sci. 2002, 83, 757-766. 

FTIR spectra of extracted wheat straw hemicellulose and cellulose do not exhibit this band (spectra not shown). From this point, the extracted wheat straw XRPP is also assigned to pectic substances. The intensity ratio of the bands i>as(COO ) at 1608 cm" and j (C 0) ester at 1740 cm corresponds to fully deesterified pectin and Me pectate... 

The FP cellulose per unit (ml) volume and enzyme yield per unit (g) cellulose or substrate obtained on wheat straw, wood, and CTMP in SSF were higher than those obtained in LSF on wheat straw and wood (Tables I, II, and III). And wheat straw proved to be a better substrate than wood for cellulose production in SSF. This could be attributed to the polysaccharides (cellulose and hemicelluloses) of wheat straw being more readily available for the organism s growth and cellulose synthesis than those of wood. The hemicelluloses and cellulose were presumably not as available in wood, because of its high lignin content and high cellulose crystallinity, as in wheat straw. 

However, oral administration of these polysaccharides had no effect. Hemi-celluloses from different higher plants caused regression of solid Sarkoma 180 in mice but not of ascites tumor. Arabinoglucuronoxylan isolated from wheat-straw hemicellulose was completely devoid of activity, whereas arabinoglucoxylan was highly active (Nakahara 31)). 

Although non-endospermic, hemicellulosic materials have often been reported to yield glucose on hydrolysis, there is little evidence of the presence of glucosyl residues in xylans. Non-cellulosic glucose occurs mainly, or exclusively, in /J-D-glucans (described later in this Section). 2,6-Di-O-methylglucose was obtained on methylation and hydrolysis of the xylans of wheat straw and com cob,132 and its presence is indicative of doubly linked glucose residues attached in some way to these xylans.132... 

The pyrolysis of wheat straw could be expected to be described by a superposition model, i.e. described by a number of parallel first order reactions, representing the decomposition of the biomass constituents (cellulose, hemicellulose and lignin) [4,5]. In this work, a superposition model has been used, in which the pyrolysis is assumed to be described by N independent first order reactions (for i=l, 2,..., N) ... 

The search for structure-function relationships was carried into many other areas of the polysaccharides, including glycogen (with M. Abdel-Akher and 0. P. Bahl) hemicelluloses of wheat straw and corn cobs (with... 

The ethanol yields obtained in this study are considerably higher than those reported for fermentation of the undetoxified hemicellulose fraction of wheat straw by various pentoseutilizing yeasts and are comparable with the highest yield of 0.41 g per gram of sugars... 

In many countries, the wheat straw is an abundant by-product from wheat production. Thus, wheat straw has potential to serve as a low-cost raw material for production of higher-value industrial products. Wheat straw is an agricultural by-product that is not used as industrial raw material at a signifieant scale in developed regions like Europe and North America. As a rough estimation, more than 170 million tons of wheat straw are produced yearly in Europe [4]. These amounts are enough to consider wheat straw as a source of renewable materials, particularly for the production of chemical derivatives from cellulose, hemicelluloses, and lignin. 

Chemical Composition of Extracted Hemicellulose of Wheat Straw... 

However, to characterize the solubilized hemicelluloses of the wheat-straw samples, the four extracted fiactions obtained and the commercial hemieellulose of birch wood (Sigma ) were hydrolyzed to determine their sugar constituents, and the results are given in Table 2. The major monosaccharide obtained was xylose of birch wood (48.1%), indicating the presence of a xylan. In the hemicelluloses of wheat straw, the major monosaccharide was arabinose (36.5%), indicating the presence of an arabinoxylan. However, these sugar concentrations were very low which can likely be due to the methodology used to determined the chemical composition of the hemieellulose extracted from wheat straw. 

Fig. 7 Scanning electron microscopy of a wheat straw (magnification, x 150) b wheat straw treated with 0.25 mol/l NaOH (magnification, xl50) c extracted hemicellulose of birch wood (magnification, x500) d extracted hemicellulose of wheat straw (magnification, x500)...

Biopolymers can be directly obtained [KOB 03] fiom hemicellulose in com or starch. Starch, a major polymer from arable crops, is a good candidate for the production of biodegradable packaging or objects. If combined with a compound of wheat straw, its potential apphcations could increase. 

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