Starch crystalline region

Presence of native starch crystals. In plant materials, starch exists as semicrystalline, granular entities. Starch molecules, both amy-lose and amy lopectin, with their many intermo-lecular hydrogen bonds, give structure to the starch granule (Zobel, 1988). The crystalline regions formed by this intermolecular hydrogen bonding are somewhat resistant to enzyme hydrolysis and need to be broken prior to enzyme treatments. 

The structure of A-type starch crystals was derived through the joint use of electron diffraction of single crystals, x-ray powder patterns decomposed into individual peaks, x-ray fiber diffraction data and extensive molecular modeling32 (Figure 5.5). The density calculated for the crystalline region (d = 1.48) is reasonably close to the observed density, and indicates that there are 12 glucosyl units and 4 water molecules in the unit cell. Intra- and inter-molecular energy calculations showed that... 

Starch is a semicrystalline polymer. The linear amylose molecules are amorphous in nature, but the branched amylopectin portion has been reported as partially crystalline. It is believed that the crystalline regions in the starch granule are interspersed in a continuous amorphous phase. ° ... 

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