Studies on Pyrodextrinization of Corn Starch Part II. A Scanning Electron Microscopic Study

A scanning electron microscopic (SEM) study of dextrin prepared in the range of 120°C to 210°C revealed cracks on the surface of some granules and burst granules indicating a gush of hot inner gas and the heat expansion on the surface. And, fused granules appeared in the dextrin prepared at higher temperature (230°C). Furthermore, the damaged granules in the dextrin were determined by rapid differential-staining method with Safranine OK 70: 100 and Direct Sky Blue 5B. The staining affinities of the granules have no relation to cracks, cavities, pin-holes and other physical appearances observed by SEM.