Structural features of arabinoxylans from sorghum having good roti-making quality

Arabinoxylans (AX) from an Indian variety of sorghum (M354) having good roti(Indian flat bread)-making quality were isolated with barium hydroxide and 10% sodium hydroxide (Hemicellulose B). Arabinoxylans from both fractions were further purified by alcohol precipitation at acidic pH and glucoamylase digestion. Structural features of the purified arabinoxylans were studied by a combination of methylation analysis involving GC-MS, C-13 NMR, oxidation studies and FT-IR spectroscopy. The results indicated a xylan backbone in beta -1,4 linkage, which is occasionally branched at O-3 or at O-2 and O-3. The branches contained arabinosyl residues in furanose form, linked mainly by alpha -1,3. Fully branched arabinosyl residues were also present. (C) 2001 Elsevier Science Ltd. All rights reserved.