One BGU is the amount of enzyme which liberates 0,15 micromoles of glucose per minute from azurine-crosslinked beta-glucan at pH 5,0 and 40 °C.. One FXU is the amount of enzyme which liberates 0,15 micromoles of xylose per minute from azurine-crosslinked xyland at pH 5,0 and at 40 °C.
This work also yielded evidence for the presence of non-starch polysaccharide hydrolysing enzymes in European wheat flours. Water extracts of flour samples prepared from sound European wheat varieties hydrolysed p-nitrophenyl-B-D-xylopyranoside and p-nitrophenyl-a-L-arabinofuranoside and, in addition, released soluble, dyed fragments from azurine crosslinked xylan. Differences in enzyme activity levels were found among wheat varieties. Incubation of water-extractable wheat arabinoxylan with water extract of flour resulted in release of low molecular weight fractions consisting mainly of L-arabinose and D-xylose and small proportions of oligosaccharides as detected by high performance anion exchange chromatography. Gel permeation profiles of the incubation mixtures showed a clear breakdown of the arabinoxylan.
