CHARACTERIZATION OF HOT-WATER-SOLUBLE COMPONENTS OF STARCHES

Starches of maize and wheat (cereals), potato (tuber), and sweet potat o (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 frac tion was a mixture of linear and branched molecules and there were mor e branches in the amyloses from potato and sweet-potato amylose than i n 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 pota to showed some similarities in properties with their normal counterpar ts, 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.