Pressed potato fibres (PPF), a by-product of starch production, has a high water-holding capacity (WHC).In this study, it is shown that the WHC is caused by a network of mainly insoluble, non-cellulosic cellwall polysaccharides (CWPs). Despite the solubilization of one-fourth of the CWPs from PPF, repre-senting 40–60 w/w% of pectic CWPs (rhamnosyl, uronyl, galactosyl and arabinosyl residues) presentin PPF, the insoluble residues still had similar WHCs as PPF. Only after enzymatic hydrolysis of mainlynon-cellulosic CWPs, the WHC decreased substantially (by 61%). Combining the cellulose-rich residueobtained after enzyme hydrolysis with a polymeric homogalacturonan (HG)-rhamnogalacturonan-I (RG-I)-arabinogalactan (AG) extract increased the WHC. This increased hydration is suggested to result fromthe observed adsorption of the soluble HG-RG-I-AG to the insoluble cellulose-rich residue. No adsorptionwas observed of the HG-RG-I-AG to an insoluble residue enriched in non-cellulosic CWPs.
- dietary fiber