ASPECTS OF THE CHEMISTRY OF CEREAL POLYSACCHARIDES

Abstract

Characteristics of starch—with its amylose and amylopectin components—are described and discussed, though it is suggested that absolute distinction between two entirely contrasting components does not exist. Considerable study has been made of the structure and biosynthesis of the starch granule, but the formulation of final conclusions on these matters is not yet possible, though there is interesting information on the apparent mode of limited amylolysis during malting. The chemistry of the hemlcelluloses is less well understood than that of the starches, though it is clearly illogical to distinguish between certain naturally-occurring gum-ike polysaccharides and so-called “typical hemicelluloses” merely on grounds of solubility. Of the cereal hemicelluloses, two general types are of wide occurrence: those with back-bone chains of β-1.4-linked xylose residues and various types of side-chain involving arabinose and glucuronic acid (often methylated), and those which comprise chains of glucose residues with β-1.3- and β-1.4-linkages in the same molecule.