ARABINOSE AND FERULIC ACID-RICH PECTIC POLYSACCHARIDES EXTRACTED FROMSUGAR-BEET PULP

Arabinose and ferulic acid rich polysaccharides were extracted from su gar beet pulp using two extraction methods: a sequential extraction wi th H2O (2 times), NaOH/EDTA (2 times), and 4 M NaOH (2 times; method A ) and a sequential extraction in which the NaOH/EDTA extraction was re placed by an autoclave extraction (2 times; method B). Both extraction method A and B yielded approximately 45% of the sugar beet pulp polys accharides. For both method A and B, three extracts with increasing ne utral sugar content were obtained: two NaOH/EDTA extracts and a 4 M Na OH extract for method A next to two autoclave extracts and a 3 M NaOH extract for method B. The sugar linkage composition indicated the pres ence of arabinose rich rhamnogalacturonan ('hairy regions') and homoga lacturonan ('smooth regions') in all extracts. The sugar compositions of the NaOH/EDTA extracts were very similar to the autoclave extracts. A remarkable difference was the higher amount of ester groups in the autoclave extracts: next to methyl esters and acetyl groups, they also contained relatively high amounts of feruloyl groups. Size-exclusion chromatography using RI- and UV-detection showed that all extracts wer e heterogeneous with respect to molecular weight distribution. Ferulic acid was particularly located in the high molecular weight population s of the autoclave extracts. (C) 1996 Elsevier Science Ltd.