Cereal Chem 54:783 - 793.  |  VIEW ARTICLE
Effect of Heating on the Freeze-Etch Ultrastructure of Hydroxypropyl Distarch Phosphate and Unmodified Tapioca Starches.

J. E. Allen, L. F. Hood, and J. F. Chabot. Copyright 1977 by the American Association of Cereal Chemists, Inc. 

The freeze-etching technique was used to study ultrastructural changes that occur during heating of hydroxypropyl distarch phosphate (modified) and unmodified tapioca starch granules in a Brabender Visco-amylograph. Prior to heating, the fracture faces of both the unmodified and modified granules had similar particulate appearances. As heating progressed, water infiltrated into the granules from the truncated end, and a starch-water reticulum formed in the central regions and subsequently enlarged throughout the granules. Swelling took place after reticulate bands were formed in the peripheral regions of the granules. These outer bands remained until the integrity of the granules was lost near peak viscosity and the gel matrix was formed. Chemical modification of the granules stabilized the outer reticulate bands and reduced the size of the interstices within the matrix.