Abstract
Wheat bran‐derived arabinoxylan‐oligosaccharides (AXOS) recently have
been shown to potentially exert prebiotic effects. In this study, 15
bran samples obtained by milling different wheat cultivars were treated
with xylanases from Hypocrea jecorina (XHJ), Aspergillus aculeatus (XAA), and Pseudoalteromonas haloplanktis
(XPH) to assess the effect of bran source and xylanase properties on
the AXOS yield and structure. The total arabinoxylan (AX) extraction
yield was higher with XHJ (8.2–10.7%) and XAA (8.2–10.8%) than with XPH
(6.9–9.5%). Irrespective of the enzyme, a significant negative
correlation was observed between extraction yield and arabinose to
xylose (A/X) ratio of bran AX (r = –0.7), but not between yield
and bran AX level. The A/X ratio of the extracted material was 0.27–0.34
for all bran samples and all enzymes, which combined with yield data
and microscopic analysis, indicated primary hydrolysis of aleurone and
nucellar epidermis AX. The average degree of polymerization (avDP) of
the extracted AX was very low for all enzymes (2–3), owing to the
release of high levels of monomeric arabinose and xylose. The release of
these monosaccharides could be ascribed to 1) the activity of wheat
bran‐associated enzymes (arabinofuranosidases and xylosidases); 2) the
hydrolytic properties of the xylanases themselves; and 3) the presence
of xylosidases as contaminations in enzyme preparation, in that order of
importance. Heat treatment of bran before xylanase treatment
significantly decreased the levels of monomeric arabinose and xylose in
the extract, without affecting the extraction yield, resulting in a
higher avDP of 3–7, thus yielding true AXOS. Overall, for AXOS
production, wheat cultivars with a low bran A/X ratio of the AX are
preferable as starting materials, and inactivation of bran‐associated
enzymes before incubation is desirable. The XHJ xylanase was the best
enzyme for wheat bran‐derived AXOS production.
Original language | English |
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Pages (from-to) | 283-291 |
Number of pages | 9 |
Journal | Cereal Chemistry |
Volume | 87 |
Issue number | 4 |
DOIs | |
Publication status | Published - Jul 2010 |
MoE publication type | A1 Journal article-refereed |