Abstract
Weaning rats were fed diets containing 59% starch granules (either laboratory prepared potato starch or commercial corn), 25% casein, 5% corn oil, 5% fiber and adequate quantity of minerals and vitamins for 3 weeks. Less growth responses (apparent body weight gain minus weight of contents of gastrointestinal tract) of rats fed the potato starch diet than those fed the corn starch diet were observed. In vitro digestibility of these starch granules to pancreatin was in order of decreasing, corn, commercial potato and laboratory prepared potato. Starch granules were separated from contents of stomach, small intestine, cecum and large intestine of rats fed the potato starch diet for either 7 or 21 days and observed under a scanning electron microscope (SEM). Pin holes of shallow and deep types were observed on the surfaces of potato starch granules isolated from stomach of rats. Sometimes, inner structures of the granules, which appeared to be terraced or step-shaped, could be seen. Many pin holes of smaller and larger sizes were visible on the surfaces of starch granules isolated from contents of small intestine of rats. Observation of the granules elucidated also, the inner structures. We could, thus, clearly show that potato starch granules were attacked by digestive enzymes of rats, probably salivary and/or pancreatic a-amylases. Potato starch granules isolated from contents of cecum of rats showed more damage than those isolated from contents of stomach or small intestine. Some starch granules isolated from contents of cecum were accompanied with cocci. These observations suggested that degradation of starch granules in cecum and large intestine depended on the attack by enzymes of enterobacteria and/or digestive enzymes of rats.*1 To whome requests for reprints should be addressed.
