The health benefits of fibre consumption are sound, but a more compressive understanding of the individual effects of different fibres is still needed. Arabinoxylan is a complex fibre that provides a wide range of health benefits strongly regulated by its chemical structure. Arabinoxylans can be found in various grains, such as wheat, barley, or corn.
Source of Arabinoxylan | Tissue Type | Total AXs (%) | WEAXs (%) | References | Main AX Structure * | References |
---|
Wheat | Endosperm | 1.52–1.75 | 0.42–0.68 | [14] | Side chains linked by α-(1→2) and/or α-(1→3) bonds along the xylan backbone. Xyloses are most commonly mono-substituted. Side chains formed mainly by single arabinose units but can contain other short sugar sidechains. |
[12][15][16][17] | [12,15,16,17] |
Bran | 11.0–16.4 | 0.54–0.95 | [14] | ||||
Barley | Endosperm | 1.2–1.3 | 0.42–0.47 | [18] | Similar structure to wheat AXs. Side chains of xylose units in the 2 and/or 3 carbon of the xyloses, which form the backbones of these AXs. Consists of more arabinose side chains than wheat AXs. | [19][20][21][22] | [19,20,21,22] |
Bran | 10.26 | - | [22] | ||||
Corn | Cob | 26.24 | - | [23] | Highly branched structures with a xylose backbone. Side chains of arabinose residues on primary and secondary hydroxyl groups. Glucuronic acid, galactose, and xylose residues can also be present. | [24][25][26] | [24,25,26] |
Bran | 26.0 | 0.71 | [27] | ||||
Rice | Endosperm | 1.83 | 0.05 | [28] | Characteristic sugar linkages and non-reducing end xylose and galactose. (1→2)-, (1→3)- or (1→5)-linked arabinose residues also present. | [29][30] | [29,30] |
Bran | 6.82 | 011 | [28] | ||||
Rye | Endosperm | 3.56–4.25 | [31] | Main chain of 4-linked β-D-xylopyranosyl residues. A terminal α-L-arabinofuranosyl residue substitutes (on average) every second unit at position 3 and a small portion of the xylose units at position 2 and 3. | [32][33][34] | [32,33,34] | |
Bran | 12.6 | 2.1 | [31] | ||||
Oat | Endosperm | 1.2 | 0.2 | [35] | (1–4)-linked β-D-xylopyranosyl residues making up the main chain, with terminal L-arabinofuranosyl residues substituting at O-3, but also at both O-2 and O-3. | [35][36] | [35,36] |
Bran | 5.2 | 0.7 | [35] |
Source | Extraction | Solvent/Enzyme | AXs Yield * | A/X Ratio | Reference |
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De-starched wheat bran | Alkali | 0.44 M NaOH | 20.80 | 0.94 | [83] |
Corn fibre | Alkali | 0.25–50 M NaOH | 26.80 ** | n.d. | [84] |
De-starched plan materials | Alkali | NaOH (pH 11.5) | 14.30–59.9 *** | n.d. | [57] |
Chinese, black-grained wheat bran residue (after removal of water-extractable polysaccharides) | Alkali | Saturated Ba(OH)2, 1% NaBH4 | ~5.8 | 0.6 | [85] |
Wheat bran | Alkali | Saturated Ba(OH)2, 0.26 M NaBH4 | 24 | 0.7 | [86] |
Corn husk | Alkali | 0.9% (w/v) Ca(OH)2 | n.d. | 0.75 | [87] |
De-starched wheat | Alkali/Enzymatic + alkali | 0.16 mol/L NaOH, 0.5% H2O2//xylanase and cellulase (sodium acetate buffer) + 0.16 mol/L NaOH, 0.5% H2O2 | 19.83//5.27 and 14.95 | 1.14//0.25 and 1.52 | [13] |
Rye bran | Alkali + enzymatic | First extraction: 0.17 M Na2CO3 or 0.17 M Ca (OH)2 or water Second extraction: xylanase |
First extraction: 2.92–3.85 Second extraction: 7.5–9.85 |
First extraction: 0.48–0.59 Second extraction: 0.23–0.28 |
[88] |
Wheat and barley straw | Alkali and steam pretreatment + enzymatic | 1–2 wt% NaOH (steam pretreatment) + β-glucosidase and xylanase | 18–35 (Wheat) 17–47 (Barley) |
n.d. | [89] |
Wheat bran | Ultrasound + Enzymatic | Xylanase (sodium acetate buffer) | 4.25–12.88 | n.d. | [66] |
Wheat bran | Enzymatic | Xylanase | 23.1 | 0.44 | [90] |
Corn fibre | Enzymatic | Xylanase and cellulase (sodium acetate buffer) | 30–45 | n.d. | [90] |
* AX extracted yield by raw material dry basis (% of Dw). ** Maximum yield achieved at optimized NaOH concentration, time, and temperature (0.5 M, 2 h, 60 °C). *** Yields were dependent on the material; yield could be influenced by pretreatments of these plant materials carried out by manufacturers. n.d.: not determined.
* AX extracted yield by raw material dry basis (% of Dw). ** Maximum yield achieved at optimized NaOH concentration, time, and temperature (0.5 M, 2 h, 60 °C). *** Yields were dependent on the material; yield could be influenced by pretreatments of these plant materials carried out by manufacturers. n.d.: not determined.