The Crystal Structures of A‐, B‐ and C‐Polymorphs of Amylose and Starch

Abstract The crystal structures of the A‐, B‐ and C‐polymorphs of amylose have been determined through a combination of fiber x‐ray diffraction analysis and computer‐based structure refinement. The three structures correspond to the naturally occurring A‐, B‐ and C‐starches. A‐ and B‐structures differ in the crystalline packing of the helices and the water content. The C‐structure is a mixture of A‐ and B‐unit cells and, therefore, intermediate between the A‐ and B‐forms in packing density.