title: Revisiting the structural features of arabinoxylans from brewers' spent grain.
abstract: The brewers' spent grain (BSG) arabinoxylans (AX) have been described to be composed by a backbone of (β1→4)-linked xylose residues containing only single units of arabinose as side chains. However, this is not in accordance with the structural features of AX from other cereal sources. Aiming to disclose the possibility of additional structural details, fractions enriched in AX were obtained by sequential extraction from BSG. The AX richest fraction was hydrolysed with xylanase, fractioned by size-exclusion chromatography, and analysed by electrospray tandem mass spectrometry (ESI-MS(n)). Methylation analysis showed that the amount of terminally linked arabinose residues was not in accordance with the number of xylose branching points. This was due to the presence of O-acetyl, hexose, hexuronic acid, and methylated uronic acid residues. AXs presenting these structural features can be a potential source of a large screening prebiotic, providing, in the same molecule, areas of fast and slow probiotic fermentation rates.
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal. Electronic address: ecoelho@ua.pt.
authors.forename: Elisabete
authors.initials: E
authors.lastname: Coelho
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: M Angélica M
authors.initials: MA
authors.lastname: Rocha
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Ana S P
authors.initials: AS
authors.lastname: Moreira
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: M Rosário M
authors.initials: MR
authors.lastname: Domingues
authors.affiliation: QOPNA, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Coimbra
mesh_terms: D000596:Amino Acids / Q000032:analysis; D002523:Edible Grain / Q000737:chemistry*; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry; D006868:Hydrolysis; D006878:Hydroxides / Q000737:chemistry; D015394:Molecular Structure; D009005:Monosaccharides / Q000032:analysis; D017680:Potassium Compounds / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014990:Xylans / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D006878:Hydroxides; D009005:Monosaccharides; D017680:Potassium Compounds; D014990:Xylans; C085118:arabinoxylan; D043364:Endo-1,4-beta Xylanases; C029943:potassium hydroxide
keywords: Acetylated arabinoxylans; Alkali extraction; Glucuronoarabinoxylans; Mass spectrometry; Size-exclusion chromatography; Xylanase