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On the Origin of a Low Angle Spacing in Starch
Author(s) -
Oostergetel Gerrit T.,
van Bruggen Ernst F. J.
Publication year - 1989
Publication title -
starch ‐ stärke
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.62
H-Index - 82
eISSN - 1521-379X
pISSN - 0038-9056
DOI - 10.1002/star.19890410903
Subject(s) - amylopectin , transmission electron microscopy , materials science , amorphous solid , starch , micrograph , bragg's law , electron diffraction , crystallography , diffraction , electron micrographs , electron microscope , optics , selected area diffraction , amylose , chemistry , nanotechnology , physics , biochemistry
The structure of starch granules from different botanical sources was studied by transmission electron microscopy and small‐angle X‐ray diffraction. Electron micrographs of negatively stained starch granule fragments show a rippled fibrous structure. The ripples are interpreted as being stacks of thin crystalline lamellae comprising the linear α‐(1→4) chains of the amylopectin. Optical diffraction analysis of the electron micrographs showed that the spacing of the ripples varies from 9.2 nm in potato starch to 10.4 nm in barley starch. This correlates well with the position of a Bragg peak at appr. 10 nm measured by small‐angle X‐ray diffraction. These observations indicate that the Bragg peak arises from the alternating amorphous and crystalline regions seen as ripples in the electron micrographs.