Analysis of the Native Structure of Starch Granules with X-ray Microfocus Diffraction

Results of microfocus X-ray diffraction at the ESRF are presented which provide unique evidence supporting a model for the structure of starch, much of this model having been previously derived only on the basis of circumstantial evidence. Here we present data from ∼2 μm regions within granules which have been subjected to no sample preparation and obtain oriented 2-D fiber patterns from the edge of B-type potato starch granules. This data is in good agreement with that previously calculated by Imberty/Perez for a B-type amylose fiber. The peripheral amylopectin helices are oriented in such a way they do not point to a single focus. No discontinuities (“grain boundaries”) within a granule could be found at the 10 μm level of resolution.