Fibrillar Structure of Starch. Evidence for Crossed Fibrils from Incipient Gelatinization

By being brought to the threshold of gelatinization through careful heating in water, grains of native potato starch often were induced to swell differentially. At 55°C, radial elements (sectors) of the interior of these grains contracted centrifugally and expanded tangentially while the rigid exterior remained mostly unswollen and therefore was burst open due to the swelling of the interior. Evidence from the light microscope, the polarizing microscope, and the scanning electron microscope showed clearly the presence of radially oriented and near radial, crossed fibrillar elements, each of which traversed many lamellae, in the ungelatinized region. No ‘core’ was evident in the burst starch grain, nor was there any separation of lamellae.