LAUSR

BACKGROUND Non-starch polysaccharides in wheat are dominated by arabinoxylan (AX). And the endo-1,4-β-xylanase (EC 3.2.1.8) is the most key enzyme to degrade AX. In this paper, the ability of an endo-1,4-β-xylanase extracted from wheat malt to degrade non-water extractable wheat-derived arabinoxylan (WUAX) was investigated. RESULTS The enzyme was observed to effectively break down wheat-derived WUAX, greatly increasing the concentration of water-extractable arabinoxylan (WEAX) in the system for up to six hours. A considerable amount of arabinose xylooligosaccharides (AXOS) was produced as well, suggesting that the enzyme could also produce oligosaccharides. The molecular weights of product WEAX were between 23 and 27 kDa and the content of oligosaccharides changed with degradation time. This suggests that the subject endo-1,4-β-xylanase can degrade not only WUAX into WEAX and xylooligosaccharides, but also xylooligosaccharides of larger molecular weight into xylobiose and xylotriose. Viscosity of the degradation product increased significantly in the first two hours, then decreased with longer degradation times. The concentration of WEAX in the reaction system increased throughout the reaction, but at gradually lower rates, indicating that the endo-1,4-β-xylanase better degraded WEAX compared to WUAX. Rheological tests showed that solutions prepared from the product WEAX had properties of a pseudoplastic fluid. CONCLUSION The results showed that the wheat malt endo-1,4-β-xylanase, which we had previously tested on WEAX, was also effective to degrade wheat-derived WUAX. Therefore, this study can provide a theoretical basis for the subsequent role of the enzyme in other sources of xylan, and provide guidance for the quality control of beer in the brewing process. This article is protected by copyright. All rights reserved.