Estimation and fractionation of the essentially un-branched (amylose) and branched (amylopectin) components of starches with concanavalin A

Conditions have been devised for the quantitative precipitation of the branched fraction in starches by concanavalin A and the enzymic estimation of the alpha-D-glucan in this and the soluble components. For some starches, such as those from cereal and high-amylose pea seeds, the percentage of branched fraction determined by this procedure was higher than that calculated by deducting from one hundred the apparent amylose content as measured by potentiometric iodine titration, suggesting a method for estimating the content of material having an atypical structure in the whole starch. The procedure has been adapted to provide a preparative method of separating amylose and amylopectin fractions. It efficiently separated these in starches that cannot be fully fractionated by complexing with 1-butanol, such as those from high-amylose pea seeds and tobacco leaves.