Structure Development in Amorphous Starch as Revealed by X-ray Scattering: Influence of the Network Structure and Water Content
The evolution of the amorphous structure of starch was characterized during the drying process by real time X-ray wide-angle scattering. The X-ray diffractograms of injection-molded starch show two superposed, rather broad, scattering maxima indicative of noncrystalline structures. The location of t...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2006 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/79482 |
| Acceso en línea: | http://hdl.handle.net/10261/79482 |
| Access Level: | acceso abierto |
| Palabra clave: | Amorphous starch Structure development WAXS |
| Sumario: | The evolution of the amorphous structure of starch was characterized during the drying process by real time X-ray wide-angle scattering. The X-ray diffractograms of injection-molded starch show two superposed, rather broad, scattering maxima indicative of noncrystalline structures. The location of the two peaks has been associated to disordered starch single helices. A third maximum that arises upon drying the material in vacuum is associated to the scattering emerging from regions containing double helices. A model for the starch network is proposed, assuming a primary and a secondary component. The wider, temperature stable component appearing first, is correlated to the entanglement network of the melt. The narrower network component, which is created later, at lower temperature (secondary network), is explained by the formation of double helix regions that densify the wider primary network. The secondary network is increased strongly by the drying process. X-ray experiments performed during the penetration of water, provoking a higher molecular mobility, reveal a better-packed helical structure that becomes the precursor of a double helix crystalline formation. When temperature increases, the secondary network is dissolved and water molecules arrange themselves in better-organized crystals as strongly bound crystal water. |
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