Gelatinization of Dieffenbachia Starch

The starch grain of Dieffenbachia seguine has the shape of an elongated, flat rod, one of whose ends is rounded and the other square. Its hilum lies near the rounded end of the grain. The molecules of the central core are parallel to the long axis of the grain while those of the peripheral layer tend to be nearly perpendicular (radial) to that axis. Gelatinization makes evident a fibrillar construction in which the fibrils of the core region are elongated parallel to the long axis of the grain while those of the periphery are crossed, at a low angle to the perpendicular. Presumably the heated starch molecules contract along their long axis, becoming randomly coiled, and thereby cause radial expansion in the core and axial and tangential expansion at the periphery of the starch grain.