Characterization of arabinose and ferulic acid rich pectic polysaccharidesand hemicelluloses from sugar beet pulp

Pectic polysaccharides were extracted from sugar beet pulp to yield fractio ns representing homogalacturonans, rhamnogalacturonans, arabinans and relat ively small amounts of glucomannans and xyloglucans. The homogalacturonans had an apparent molecular weight of 21 kDa and contained relatively high am ounts of methyl esters and relatively low amounts of acetyl groups as compa red with the ramified 'hairy' regions. Three populations which originated f rom the ramified 'hairy' regions of pectin were distinguished. Two of these were rhamnogalacturonans with high apparent molecular weights of 1300 and 120 kDa, respectively. These populations had a high Ara and ferulic acid co ntent. Despite the high neutral sugar content, these rhamnogalacturonans st rongly bound to a DEAL column. The third population which originated from t he ramified 'hairy' regions was a neutral population, which did not interac t with the DEAE column and had a low apparent molecular weight and a high A ra and ferulic acid content. The arabinan side-chains of the rhamnogalactur onans were heavily branched in all populations. Enzymatic degradation of th e xyloglucans showed similarities with apple xyloglucans with respect to th e substitution with Fuc and Gal. (C) 2000 Elsevier Science Ltd. All rights reserved.