Separation of amylose from amylopectin of starch by an extraction‐sedimentation procedure

Abstract

Abstract Corn, wheat, and potato starch were fractionated into their amylose and amylopectin components by selective extraction of amylose in hot water after the starch had been pretreated by heating in aqueous mixtures of glycerol, n ‐butanol, Pentasol, Cellosolve, or dioxane. About three‐fourths of the amylose was leached in relatively pure form from starch in the first extraction at 98°C. The granule residue, sedimented by centrifugation, was separated as relatively pure amylopectin after two or more additional extractions. Retention of the coherent structure of the granule in the extracted residue emphasizes the importance of amylopectin to granule properties. Amylose fractions isolated from successive extractions had progressively lower intrinsic viscosities and absorption coefficients of their iodine complexes indicating that this component was subfractionated according to molecular size and/or structure. X‐ray diffraction patterns of the pretreated starches indicated that a complex of amylose and organic solvent was formed which may account for the increased solubility of amylose after pretreatment. Evidence is presented which shows that little, if any, amylose occurs in the crystalline regions of granular starches.