Arabinoxylans

Arabinoxylans are a class of non-starch polysaccharides that constitute a major portion of plant cell wall hemicellulose. They consist of a β-(1→4)-D-xylopyranose backbone with side chains of α-L-arabinofuranose attached to the xylose units, mainly at the O-2 and/or O-3 positions. The arabinose-to-xylose ratio (A/X) and the degree of feruloylation vary with plant source and determine solubility, viscosity, and cross-linking potential.

In cereals, arabinoxylans are particularly abundant in wheat, rye, barley, and oats, especially in bran fractions. They are present in both soluble and insoluble forms and contribute significantly to dietary fiber intake and the functional properties of doughs.

The rheology of arabinoxylans is influenced by chain length, branching, and bound hydroxycinnamic acids such as ferulic acid, which can form cross-links between AX chains and to lignin, affecting solubility and gel formation. Soluble AX increase viscosity in solution, while insoluble AX contribute to water-holding capacity.

Dietarily, arabinoxylans are fermentable by gut microbiota, producing short-chain fatty acids and acting as prebiotic substrates. They can modulate glycemic response and mineral absorption. In the food industry, AX serve as hydrocolloids that modify dough rheology, crumb structure, and crumb moisture; they are investigated for gluten-free formulations and as dietary fibers.

AX are commonly extracted from cereal bran by alkaline treatment or enzyme-assisted methods; they are quantified by chromatographic or colorimetric assays. Important analytical parameters include the A/X ratio and the bound ferulic acid content, which reflect substitution and cross-linking potential.