Characterisation of hot-water-soluble components of starches

Abstract Starches of maize and wheat (cereals), potato (tuber), and sweet potato (rhizome) were extracted by 6 mM phosphate buffer (pH 6.2) above the gelatinisation temperatures, and fractionated into amylose (1-butanol precipitate) and amylopectin (supernatant solution). The amylose fraction was a mixture of linear and branched molecules and there were more branches in the amyloses from potato and sweet-potato amylose than in those from maize and wheat. The preponderant branches were short and probably clustered around the reducing terminal of the molecule. The amylose molecules in potato and sweet potato were larger than those in maize and wheat. The amylopectin fractions from potato and sweet potato showed some similarities in properties with their normal counterparts, whereas those of maize and wheat differed remarkably and contained considerable proportions of an unusual and novel fraction with dp 240 and 215, respectively, which may reflect the conditions of extraction and the botanical origin of the starch.