1. Biochemical characterisation of cellulose and cell-wall-matrix polysaccharides in variously oxidised sugar-beet pulp preparations differing in viscosity.
- Author
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Whale E, Bulling AEK, and Fry SC
- Subjects
- Viscosity, Polysaccharides chemistry, Pectins chemistry, Glucose, Water, Cellulose chemistry, Beta vulgaris chemistry
- Abstract
Sugar-beet pulp (SBP) is an abundant, cellulose-rich, non-food by-product of agriculture. Oxidised SBP (oP) has valuable viscosity attributes, and different oxidation protocols yield higher- or lower-viscosity oP. We investigated how SBP polysaccharides change during oxidation, since these changes must define oP quality. Oxidation solubilised much pectin and hemicellulose; however, most cellulose stayed insoluble. Fresh SBP contains negligible 'hemicellulose a' (=alkali-extractable polysaccharides that precipitate upon acidification), but oxidation created abundant glucose-rich 'hemicellulose a' from SBP cellulose. We propose that the cellulose acquired COOH groups, conferring alkali-extractability and admitting more water, thereby augmenting viscosity. The pectin and hemicellulose molecules that were retained during oxidation had been partially depolymerised, and their median M
r correlated negatively with oP viscosity. We developed a novel procedure to explore cellulose's permeability by measuring the ingress of tritium from [3 H]water into microfibrils and its retention during desiccation. In high-crystallinity Avicel, 75 % of the cellulose's OH groups were inaccessible to [3 H]water, whereas filter-paper cellulose acquired the theoretical maximum3 H, indicating an open structure. Retention of3 H by oP preparations correlated positively with viscosity, indicating that increased cellulose accessibility generates a viscous oP. In conclusion, depolymerisation and solubilisation of matrix polysaccharides, accompanied by increasing water-accessibility of cellulose, enhanced SBP's viscosity., Competing Interests: Declaration of competing interest The authors declare that they have no conflict of interest. Patents have been filed by CelluComp Limited covering cellulose particulate material (WO2014147392A1, WO2014147393A, US10246522B2, US10131715B2, US10808044B2, US10894890B2) and the method for preparing cellulose-containing particles (WO2017220777A1, JP7050011B2); E.W. is one of the inventors., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2023
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