Characterization of arabinoxylan degrading enzymes during wheat malting

¹ College of Food Science and Engineering, Shandong Agricultural University, No. 61 Daizong Street, Tai'an, 271018, Shandong
² Department of Modern Services，Rizhao Technician College, No. 2 Linyi North Road, Rizhao, 276800, Shandong Province, PR China
³ Tai’an Tai shan Beer Co., No. 99 Keji North Street, Tai'an, 271000, Shandong Province, PR China

^# The first two authors contributed equally to this work.
^* Corresponding author: yuhongjin79@sdau.edu.cn

Abstract

In this paper the arabinoxylanase activities and the content of water-extractable arabinoxylans (WEAXs) including their degradation products in wheat Yannong 24 during the malting process were studied. The results showed that the endo-β-1,4-xylanase activity had a large increase during the steeping process, endo-β-1,4-xylanase and α-L-arabinofuranosidase achieved the highest activity on day 4 of germination. During malt kilning, endo-β-1,4-xylanase and α-L- arabinofuranosidase were not heat stable, and the activity decline rate were 65.88% and 69.58%; whereas malt β-D-xylosidase was resistant to heat and it’s activity decline rate was only 18.74%. It is during steeping and the first day of germination that the content of WEAXs and it’s degradation products (WEAXs+DP) dramatically increased, and this corresponded to the greater improvement of endo-β-1,4-xylanase activity in the same phase. The WEAXs+DP content has a very significant positive correlation with the endo-β-1,4-xylanase activity (0.892, p<0.01). It can be indicated that endo-β-1,4-xylanase is the main degrading enzyme in the degradation of WUAXs and the increase of the WEAXs content during steeping and the first day of wheat germination.