Isolation and characterization of high molar mass water-soluble arabinoxylans from barley and barley malt

• Published in: Carbohydrate polymers Vol. 47; no. 2; pp. 143 - 149
• Main Authors: Dervilly, G, Leclercq, C, Zimmermann, D, Roue, C, Thibault, J.-F, Saulnier, L
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2002; Elsevier Science; Elsevier
• Subjects: Applied sciences; Arabinoxylans; Barley; Beers; Biological and medical sciences; Brewing; Chemical Sciences; Exact sciences and technology; Fermented food industries; Food industries; Fundamental and applied biological sciences. Psychology; Malting; Natural polymers; Physicochemistry of polymers; Polymers; Starch and polysaccharides; Viscosity; Viscosity; MALLS: multi-angle laser light scattering; Malting; Xyl p: xylopyranose; Ara: arabinose; HPSEC: high performance size-exclusion chromatography; u-Xyl: un-substituted xylose; BSA: bovine serum albumin; Glc: glucose; [ η]: intrinsic viscosity; GLC: gas liquid chromatography; molar mass; AX: arabinoxylans; Man: mannose; 2,3-Xyl: 2-O, 3-O-substituted xylose; HPLC: high performance liquid chromatography; R G: radius of gyration; Arabinoxylans; Barley; SEC: size-exclusion chromatography; Araf: arabinofuranose; 2-Xyl: 2-O-substituted xylose; AG: arabinogalactans; 3-Xyl: 3-O-substituted xylose; Brewing; Gal: galactose; Ara/Xyl: arabinose to xylose ratio; NMR: nuclear magnetic resonance; Xyl: xylose; DP: polymerization degree; Fractionation; Molecular structure; Intrinsic viscosity; Chemical isolation; Experimental study; Plant origin; Physical separation; Malt; Oside polymer; Aqueous solution; Conformation; Weight average molecular weight
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/S0144-8617(01)00172-2

Water-soluble arabinoxylans have been fractionated from barley and barley malt by size exclusion chromatography to obtain high molar mass arabinoxylans involved in the viscosity of wort and beer. In both cases, five fractions were obtained: AXb 1, AXb 2, AXb 3, AXb 4 and AXb 5 for barley and AXm 1, AXm 2, AXm 3, AXm 4 and AXm 5 for barley malt. For barley and malt fractions, Ara/Xyl ratio, molar mass and intrinsic viscosity decreased as their elution volume increased. M ̄ w of barley fractions were higher than that of malt fractions, attesting arabinoxylans degradation during malting. NMR and methylation studies revealed that whatever the fractions, approximately 50% of the xylose residues were un-substituted. 2,3-Xyl level decreased from AXb 1 to AXb 5 and from AXm 1 to AXm 5, whereas 3-Xyl level increased at the same time. A non negligible amount of 2-Xyl was found, this level being almost the same (6–8%) for all the fractions. AXm 1, which exhibited the highest intrinsic viscosity, (240 ml/g) was considered as an interesting fraction with regard to brewing problems. In spite of its highly branched structure, AXm 1 was easily degraded by xylanases. Evidence for the presence of ferulic acid dimers in the water-soluble arabinoxylans from barley and barley malt is provided.