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 similar to 2 mu m 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(1) 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 mu m level of resolution.