Arabinoxylan and Arabinoxylan Hydrolysing Activities in Barley Malts and Worts Derived from Them

Abstract The water-extractable and total arabinoxylan contents of six barley malts varied between 0·49–0·69% (all analytical data expressed as a proportion of dry malt) and 6·40–6·93% respectively. Centrifuged wort arabinoxylan (0·62–0·93%) represented 10 to 14% of the total barley malt arabinoxylan. During brewing some monomeric arabinose (ara) (0·02–0·03%) and xylose (xyl) (0·03–0·06%) were released. There was a linear relationship (R 2 = 0·65; n = 6) between the centrifuged wort arabinoxylan contents and endoxylanase activities in the malts as well as between the levels of arabinoxylan solubilised during brewing and the endoxylanase activities of malts (R 2 = 0·88; n = 6). The levels of monomeric xyl released during brewing were also related in a linear way (R 2 = 0·92; n = 6) to the β- d -xylosidase activities. The levels of monomeric ara released were not directly related to α- l -arabinofuranosidase activities (R 2 = 0·28; n = 6).