Wheat straw products

Tanaka, D.L., 1995. Spring wheat straw production and composition as influenced by topsoil removal. Soil Sci. Soc. Am. J. 59, 649-654. 

Potential resources of xylans are by-products produced in forestry and the pulp and paper industries (forest chips, wood meal and shavings), where GX and AGX comprise 25-35% of the biomass as well as annual crops (straw, stalks, husk, hulls, bran, etc.), which consist of 25-50% AX, AGX, GAX, and CHX [4]. New results were reported for xylans isolated from flax fiber [16,68], abaca fiber [69], wheat straw [70,71], sugar beet pulp [21,72], sugarcane bagasse [73], rice straw [74], wheat bran [35,75], and jute bast fiber [18]. Recently, about 39% hemicelluloses were extracted from vetiver grasses [76]. 

There is growing interest in the use of cereal straws such as wheat straw for animal feed after increasing its digestibility by various methods, or as a raw material for paper and board production. This is particularly important in areas with limited forest resources (1). For all these purposes a good physicochemical characterisation of cereal straw is necessary. 

Other workers140 have also examined the products derived by hydrolysis of periodate-oxidized xylan. Both wheat straw and com cob xylan, after oxidation and hydrolysis, yield small amounts of L-arabinose and D-xylose. These sugars are obtained even after the xylans have been subjected to extended periods of oxidation. It is concluded that the D-xylose constituted branch points in the xylan. Likewise, the L-arabi-nose molecules must not have been terminal units in a xylan chain but must have been either interior units in the xylan molecule or have constituted an araban-like polysaccharide which is in combination or admixture with the xylan polysaccharide. 

Table 7.17. Input and output data for the production of ethanol from wheat straw...

Anaerobic digestion yields of the slurries are given in Table 2.5. Due to the higher proportion of lipids in manure, the methane production is higher than in wheat straw. The total amounts of lipid and protein, in particular, are lower in straw than in manure and thus the theoretical methane yield is significantly lower in wheat straw than in manure (Table 2.5). The average methane yields of manure and wheat straw were 14.7% and 10.4% of volatile solids, respectively (Demirbas and Ozturk, 2004). 

When wheat straw was fermented in LSF, the FP cellulase level reached 6 lU/ml (300 lU/g cellulose or 120 lU/g substrate) (Table I) by day 11, decreasing thereafter. This showed that SSF was better than LSF for cellulase production when using wheat straw. 

Table I. Cellulase Production on Wheat Straw with Trichoderma reesd QMY-1...

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. 

Wheat straw. FP cellulase per unit volume in LSF was very low at 1% wheat straw. It doubled when the wheat straw concentration was raised to 5%. But the FP cellulase per unit weight of wheat straw produced at 5% concentration was reduced to almost one-half that obtained on 1%. Similar observations were made with the )3-glucosidase and xylanase activities (Table IV). The low productivity of all the enzymes could be the result of an O2 transfer problem in the thick fermentation medium in the LSF. 

Figure 2. Hydrolysis products of beechwood O-acetylglucuronoxylan (Fig. 2a), beechwood glucuronoxylan (Fig. 2b), and wheat straw arabinoxylan (Fig. 2c), as analyzed by gel permeation chromatography. The hydrolysis was carried out at pH 5 at 45°C for 24 h using 10.000 nkat of the 20 kDa xylanase of T. reesei. X = xylose X2 = xylobiose Xmga — 4-O-methyl-glucuronosyl substituted xylo-oligosaccharides X = xylo-oligosaccharides DP > 20.

The estimated quantities of removable corn stover and wheat straw presented in Tables 7 and 8 conform to intuitive expectations in that as tillage operations become less intensive (i.e., go from conventional to no-till), the amounts of removable residue increase across all rotations in all states. Differences in estimated removable quantities among states is a function of several factors including production location (whether the majority of production occurs in areas that have highly erodible soils and field topology nonconducive to removal), climatic/erosive conditions at the locations of production, and actual yields at these specific locations among others. These factors must be considered before residues can be removed at any specific location. 

Fungal Upgrading of Wheat Straw for Straw-Thermoplastics Production... 

To evaluate how the formulation components affect extrusion product performance, a fractional factorial design was created for statistical analysis. The fractional design is shown for the Neat and treated straw composite testing in Table 2. As already noted, Degradel and Degrade2 represent wheat straw that was inoculated with P. ostreatus and incubated for 6 and 12 wk, respectively. The values in Table 2 are percentages required to make a 2-kg batch for extrusion. 

The experimental data presented herein are the result of exploratory research aimed at bracketing the necessary moisture and inoculum loads for effective pilot-scale distributed upgrading of wheat straw stems for production of straw-thermoplastic composites (4,15). An exploratory approach was chosen for these tests because full-scale outdoor systems having few environmental controls would be difficult if not impossible to closely control. Both temperature and moisture levels vary owing to variations in heat,... 

Recent studies have proven ethanol to be an ideal liquid fuel for transportation and renewable lignocellulosic biomass to be an attractive feedstock for ethanol fuel production by fermentation (1,2). The major fermentable sugars from hydrolysis of lignocellulosic biomass, such as rice and wheat straw, sugarcane bagasse, corn stover, corn fiber, softwood, hardwood, and grasses, are D-glucose and D-xylose except that softwood... 

Chang, C., Cen, P. and Ma X. 2007. Levulinic Acid Production from Wheat Straw. Biores. Technol., 98, 1448-1453. 

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