The fractionation of potato starch part IV. The absorption spectra and colour intensities of the starch‐iodine complexes

The absorption spectra given by the starch‐iodine complexes of the potato starch fractions are qualitatively very similar to those previously observed for the wheat starch fractions. The earlier C.W. Sol. Potato starch fractions are richer in amylose but poorer in amylopectin than the corresponding H.W. Sol. fractions; in contrast, the reverse distribution is obtained for wheat starch, the early C.W. Sol. fractions being much poorer in amylose, and correspondingly rich in amylopectin than the H.W. Sol. fractions. Depolymerization of both starches by grinding lowers the absorption of the starch‐iodine complex only at the longer visible wavelengths.