On Structural Difference in Amylopectins from Different Origins Reflected upon the Shapes of Amperometric Iodine Titration Curve

Abstract

As previously reported, potato starch gives a refracting point on the sharply ascending part in its amperometric iodine titration curve, but corn starch gives no such point. It has been considered that the difference between these two kinds of starches is not due to their amylose components but to amylopectin components. In the present paper, the difference between the amylopectins was examined from two points of view: (1) it was considered that the esterified phosphate on starch molecules is independent of the difference in shapes of the titration curves, because the high phosphate corn starches prepared by roasting corn starch with sodium phosphates still gives no refracting point on the curves; (2) it was considered that the difference between the titration curves is dependent of some structural difference in inner part of amylopectin molecules, because β-limit dextrin from potato amylopectin gives essentially the same shape of the titration curve as that of the original amylopectin.