Amylopectin of waxy starch has a larger molecular weight than that of the normal starch counterpart. Amylose is located side by side, interspersed and intertwined with amylopectin in the normal starch granule. The structures of amylopectin, Naegeli/Lintner dextrin, and starch granules indicate that the short branch-chains of amylopectin, which are located in the middle of the crystalline region of amylopectin, are responsible for the starch crystallization into the orthorhombic unit cell and display the A-type polymorphism. The A-type polymorphic starch also shows voids in the granule, which increase access of enzyme hydrolysis and chemical penetration into the granule. Recent advances in the understanding of the structure of amylopectin and Naegeli/Lintner dextrin are summarized in the chapter. The mechanisms of starch crystallization and the formation of voids in the A-type polymorphic starch are proposed and discussed.
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