Wheat straw molecular weight

Feruloyl esterase activity was first detected in culture filtrates of Strepto-myces olivochromogenes (49), and has thereafter also been reported for some hemicellulolytic fungi (Table III). A partially purified feruloyl esterase from S. commune liberated hardly any ferulic acid without the presence of xylanase (65). Very recently a feruloyl esterase was purified from Aspergillus oryzae (Tenkanen, M. Schuseil, J. Puls, J. Poutanen, K., /. Biotechnol, in press). The enzyme is an acidic monomeric protein having an isoelectric point of 3.6 and a molecular weight of 30 kDa. It has wide substrate specificity, liberating ferulic, p-coumaric, and acetic acids from steam-extracted wheat straw arabinoxylan. 

Ben-Ghedalia, B., Yosef, E. Effect of isolation procedure on molecular weight distribution of wheat straw lignins. J. Agric. Food Chem. 42, 649-652 (1994)... 

Xylans can be coextracted from wheat straw and bran in a twin-screw extruder. The best results for both the production yield and the extract properties are obtained with low alkali content, as the majority of the xylans conies from bran. The desired concentration of the extract solution can be achieved by ultrafiltration. The membrane configuration and molecular weight cut off (MWCO) must be adapted to each solution to limit fouling and concentration polarisation. A permeate flux of 20 dmVh.nr was obtained at a final concentration ratio of 2. Ultrafiltration allows for a partial demineralization of the solutions but does not change the properties of the final powder. 

Similarly wheat straw, another annually replenishable biomass resource available in many countries, contains about 35-38% hemicellulose (Sun and Tomkinson, 2002). Extraction of this hemicellulose, containing about 70% xylose, 13% arabinose and 14% gluclose by an ultrasound irradiation technique, improved the molecular weight as well as the thermal stability of the hemicellulose, and is a promising technique if used in conjunction with other techniques such as steam explosion . This will enable the extraction of hemicellulose in such a form that the chemical structure will be as little changed as possible from the native state. 

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