The ultrastructure of unmodified and chemically‐modified tapioca starch granules as revealed by the freeze‐etching technique

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Abstract
Summary: The ultrastructure of tapioca starch granules was studied using the freezeetching technique in an attempt to overcome the problems associated with the other methods of preparation for electron microscopy. A chemically‐modified tapioca starch was also studied to ascertain whether chemical modification affected granule structure. Variations in fracture faces were observed in both modified and unmodified granules suggesting that organization within the granules was not homogenous. Particles were present on granule fracture faces. the size range of the particles was 4 to 10 nm in the unmodified and 6 to 15 nm in the modified granules. These observations were similar to those found by others in freeze‐etched starch granules and must be considered to be of some structural significance. In contrast to the fracture face, the outer surface of the granules was smooth and particles were not evident.