Debranning of wheat prior to milling reduces xylanase but not xylanase inhibitor activities in wholemeal and flour

Debranning of wheat to remove the outer 7% of the kernel, prior to grinding or milling reduced xylanase activity in wheat wholemeal and wheat endosperm flour by up to 80 and 60%, respectively, whereas there was no significant reduction of xylanase inhibiting activity. Flours obtained after debranning and milling showed no major differences in moisture content, whereas ash content decreased and protein and arabinoxylan content decreased slightly with increasing debranning degree. Part of the xylanase activity in the flour was lost on addition of Triticum aestivum xylanase inhibitor (TAXI). Since TAXI specifically inhibits glycosyl hydrolase family 11 xylanases and since endogenous cereal xylanases belong exclusively to family 10, part of the xylanase activity in the flour is most likely of microbial origin. Debranning also significantly reduced alpha-amylase activities in wheat wholemeal and wheat flour. Debranning prior to milling can, therefore, impact on flour functionality. (C) 2004 Elsevier Ltd. All rights reserved.