Effect of pretreatment on arabinoxylan distribution in wheat bran

• Immunolocalization was used to map the arabinoxylan distribution in wheat bran.
• The spatial carbohydrate distribution was assessed by labeling, peeling and methanolysis.
• A very simple immunolabeling method for the soft bran flakes is presented.
• Chemical, mechanical and enzymatic treatments changed the arabinoxylan distribution.
• Ball milling was the most beneficial treatment to obtain arabinoxylan.

Arabinoxylan is one of the potential key products of a wheat bran based biorefinery. To develop a suitable process for the isolation of arabinoxylans, the effect of different processing approaches needs to be determined. In this work, chemical analysis was supplemented by immunolocalization of arabinoxylan by confocal microscopy, which proved valuable in the assessment of cell-structural changes occurring upon different chemical and mechanical bran treatments. The influences of acid, lye and hydrogen peroxide treatment, ball-milling, extrusion, fermentation and treatment with esterase, xylanase and a combination thereof were investigated.Extensive ball-milling showed the best selectivity for harvesting arabinoxylan. Chemical treatments gave the highest yields, but did so at the cost of selectivity. Fermentative and enzymatic treatments were hampered by coextraction of other compounds.