Volume 60, Issue 9 pp. 476-484
Research Paper

Temperature Related Structural Changes in Wheat and Corn Starch Granules and Their Effects on Gels and Dry Foam

Gregory M. Glenn

Corresponding Author

Gregory M. Glenn

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, 800 Buchanan St., Albany, CA 94710, USA. Phone +-1-510-559-5677, Fax: +1-510-559-5936Search for more papers by this author
Artur Klamczynski

Artur Klamczynski

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

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Bor-Sen. Chiou

Bor-Sen. Chiou

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

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William J. Orts

William J. Orts

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

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Syed H. Imam

Syed H. Imam

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

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Delilah F. Wood

Delilah F. Wood

United States Department of Agriculture, Agricultural Research Service, Western Regional Research Center, Albany, CA, USA

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First published: 02 September 2008
Citations: 29

Abstract

The effect of processing temperature on structural changes in wheat, corn, and high amylose corn starch granules was investigated and related to the mechanical properties of gels and microcellular foam (MCF). Scanning electron micrographs (SEM) showed that wheat starch granules form ghosts with thicker walls than dent corn granules. The granule wall was permeable to water and appeared to be at least partially permeable to the solubilized contents of the granule. The ghost walls became visibly porous after heating at 95ºC for 60 min and were completely solubilized by heating to 120ºC. High-amylose corn starch (HACS) granules were completely dissolved by heating to 140ºC. Gels made with wheat starch had higher gel strength and dynamic modulus compared to dent corn starch gels. The density, compressive strength and modulus of MCF were lower in samples cooked for 60 min. The density of dent corn MCF was higher than that of wheat starch which may have accounted for higher compressive strength and modulus in the corn sample. MCF made from HACS had higher surface area and lower density, compressive strength, and modulus than the other starches tested. There were no significant differences in pore volume or surface area due to extended cooking times.

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