title: Soybean (Glycine max) cell wall composition and availability to feed enzymes.
abstract: Defatted untoasted soybean cotyledons and hulls were fractionated as water solutes (WSc and WSh) and water unextractable (WUc and WUh). Further fractionation of WUc through deproteinization yielded the isolation of a water unextractable solid (WUS) fraction that was mainly composed (molar percent) of galactose (28.1%), glucose (27.8%), arabinose (13.3%), and uronic acids (17.6%), which accounted for 76% of the water insoluble polysaccharides in soybean cotyledons (WUc). The cell wall (WUS) was sequentially fractionated with chelating agents (chelating agent soluble solids, ChSS) and a gradient of agents (dilute alkali, DASS; 1 M alkali, 1MASS; and 4M alkali, 4MASS), which gave a final cellulosic residue. The ChSS and DASS extracts were characterized as pectin-rich fractions, whereas 1MASS and 4MASS were hemicellulose- and cellulose-rich fractions. Incubation in vitro of the WUc fraction with pectinase, cellulase, and xylanase resulted in the release of low amounts (not more than 5% bound basis) of monosaccharides, mostly uronic acids, xylose, and arabinose. Protein extraction hardly increased this release after enzymatic incubation (<7%). However, progressive fractionation of the cell wall matrix markedly increased the release of monosaccharides from pectin- (ChSS and DASS) and hemicellulose-rich fractions (1MASS and 4MASS). Significant degradation of cellulose (up to 20%) was achieved only after complete protein, pectin, and hemicellulose extraction.
authors.affiliation: Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Bellaterra E-08193, Barcelona, Spain.
authors.forename: Imed
authors.initials: I
authors.lastname: Ouhida
authors.forename: Jose F
authors.initials: JF
authors.lastname: Pérez
authors.forename: Josep
authors.initials: J
authors.lastname: Gasa
mesh_terms: D001089:Arabinose / Q000032:analysis / Q000378:metabolism; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D002480:Cellulase / Q000378:metabolism; D002482:Cellulose / Q000032:analysis / Q000378:metabolism; D002614:Chelating Agents; D005591:Chemical Fractionation; D010368:Pectins / Q000032:analysis; D011096:Polygalacturonase / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis / Q000378:metabolism; D013025:Glycine max / Q000737:chemistry*; D014574:Uronic Acids / Q000032:analysis / Q000378:metabolism; D043325:Xylan Endo-1,3-beta-Xylosidase; D014994:Xylose / Q000032:analysis / Q000378:metabolism; D014995:Xylosidases / Q000378:metabolism
chemical_list: D002614:Chelating Agents; D011134:Polysaccharides; D014574:Uronic Acids; C007916:hemicellulose; D010368:Pectins; D002482:Cellulose; D014994:Xylose; D001089:Arabinose; D014995:Xylosidases; D011096:Polygalacturonase; D043325:Xylan Endo-1,3-beta-Xylosidase; D002480:Cellulase