Cereal Chem 53:85 - 90.  |  VIEW ARTICLE
Effect of Chemical Modifications on the Ultrastructure of Corn, Waxy Maize, and Tapioca Starches.

J. F. Chabot, L. F. Hood, and J. E. Allen. Copyright 1976 by the American Association of Cereal Chemists, Inc. 

Unmodified and modified tapioca, corn, and waxy maize starches were examined with light and electron (scanning and transmission) microscopy. Modified starches investigated included those cross-linked with POC13 or epichlorohydrin, and/or derivatized with propylene oxide or acetic anhydride. Only slight differences were noted in the structure of granules cross-linked with different reagents. Some samples of uncooked modified starches showed granule breakage and partial gelatinization. Gelatinized preparations of unmodified tapioca consisted of few granules and a mass of interconnected fibrils of variable dimension. Hydroxypropyl distarch phosphate and acetylated distarch glycerol from tapioca had intact granules containing a diffuse material as well as intergranular fibrils. Unmodified waxy maize and all modified waxy maize starches had little or no extragranular fibrillar material. Unmodified and modified corn had small granules embedded in a fine fibrillar matrix. Some of the modified granules also had diffuse fribrillar material in the central cavity of the granule. Chemical modification of corn and tapioca starch caused a reduction in the amount of extragranular starch, with the maintenance during cooking of an intact envelope around a fibrillar filled cavity.