isolation and analysis of cell wall material from the alcohol-insoluble residue of cabbage (Brassica oleracea var. capitata)

Cell wall material (CWM) was isolated from the wet ball‐milled alcohol‐insoluble residue of cabbage by treatment with Pronase, phenol‐acetic acid‐water and 90% aqueous dimethyl sulphoxide to remove precipitated proteins, starch and other intracellular compounds. Some solubilisation (mainly of pectic material) occurred during the purification stages. Methylation analysis of the cold water‐soluble polysaccharides showed that the main neutral glycosidic linkages in descending order of concentration, were: non‐reducing terminal arabinose groups, 5‐linked arabinose and 4‐linked galactose. The CWM contained a high level of arabinose‐containing pectic polysaccharides. The main linkages present in the non‐cellulosic polysaccharides were 4‐linked galacturonic acid, non‐reducing terminal arabinose groups and 5‐linked arabinose; doubly branched arabinose residues were also present. Sequential extraction of the CWM by aqueous inorganic solvents yielded further information on the types of polysaccharides present. The general structural features of the CWM are discussed in the light of these results.