Arabinoxylan hydrolysis products

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 role of arabinosyl substituents and the need for a-arabinosidase in the production of xylose from arabinoxylan was also deduced from the results in Table II. When the purified 20 kDa xylanase and / -xylosidase were used in the hydrolysis, the xylose yield was only 66% of that produced by the whole culture filtrate at the same activity levels, and no arabinose was produced. Addition of a-arabinosidase increased the yields of both xylose and arabinose. 

XOS are manufactured by enzymatic hydrolysis of xylan from corn cobs, oat spelt xylan or wheat arabinoxylan [257]. Xylan, a principle t)q)e of hemicellulose exists as a linear polymer of -D-xylopyranosyl units linked by 1 4 glycosidic bonds. Depending on the origin, different substituents such as arabinfuranosyl, 4-0-methylglucuronosyl and acetyl groups are present. Typical raw materials for XOS production include hardwoods, com cobs, straws. 

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