Ouhida Imed, Pérez Jose F, Gasa Josep
Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Bellaterra E-08193, Barcelona, Spain.
J Agric Food Chem. 2002 Mar 27;50(7):1933-8. doi: 10.1021/jf010686u.
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.
将脱脂未烘烤的大豆子叶和豆皮分别分离为水溶性部分（WSc和WSh）和水不溶性部分（WUc和WUh）。通过脱蛋白对WUc进一步分离，得到一种水不溶性固体（WUS）部分，其主要由（摩尔百分比）半乳糖（28.1%）、葡萄糖（27.8%）、阿拉伯糖（13.3%）和糖醛酸（17.6%）组成，这些成分占大豆子叶中水不溶性多糖（WUc）的76%。细胞壁（WUS）依次用螯合剂（螯合剂可溶性固体，ChSS）和一系列试剂（稀碱，DASS；1M碱，1MASS；和4M碱，4MASS）进行分离，得到最终的纤维素残渣。ChSS和DASS提取物的特征是富含果胶的部分，而1MASS和4MASS是富含半纤维素和纤维素的部分。在体外将WUc部分与果胶酶、纤维素酶和木聚糖酶一起孵育，导致释放少量（不超过5%结合基准）的单糖，主要是糖醛酸、木糖和阿拉伯糖。酶孵育后蛋白质提取几乎没有增加这种释放（<7%）。然而，细胞壁基质的逐步分离显著增加了果胶（ChSS和DASS）和富含半纤维素部分（1MASS和4MASS）中单糖的释放。仅在完全提取蛋白质、果胶和半纤维素后，纤维素才会有显著降解（高达20%）。
