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United States Department of Agriculture

Agricultural Research Service

Title: Formation of Crystalline Aggregates in Slowly-Cooled Starch Solutions Prepared by Steam Jet Cooking

Authors
item Fanta, George
item Felker, Frederick
item Shogren, Randal

Submitted to: Carbohydrate Polymers
Publication Type: Patent Application
Publication Acceptance Date: March 28, 2001
Publication Date: N/A

Interpretive Summary: When water dispersions of cereal starch are passed through a steam jet cooker, and the hot solutions are allowed to cool, crystalline particles are formed in yields ranging from 7-12%. Two particle types are formed from corn starch and rice starch, and each of these has its own unique size, shape and surface texture. The smaller sized particles are disc- or torus-shaped and often exhibit spiral surface striations. The larger particles are approximately spherical in shape and have rough surface textures. Wheat starch yields only a single small-particle species. Experimental evidence suggests that these particles result from crystalliz- ation of complexes formed from the amylose component of starch and the native lipid material present in cereal starch granules. End use applications for these materials are being sought.

Technical Abstract: Spherocrystalline particles were formed in dilute, jet cooked solutions of normal cornstarch, high amylose cornstarch, rice starch and wheat starch, when hot solutions were allowed to slowly cool in insulated Dewar flasks. Yields ranged from approximately 7-12%, and particles were composed largely of amylose. Spherocrystals were not obtained from waxy cornstarch, defatted cornstarch or potato starch. Normal cornstarch, high amylose cornstarch and rice starch yielded mixtures of two different particulate species, each having its own unique size and morphology. Both species were strongly birefringent, and no significant loss of bire- fringence was observed when particles produced from normal cornstarch were heated in water to 97-99 degrees C. SEM showed that smaller-sized particles were disc- or torus-shaped and often exhibited spiral surface striations. The larger particles were approximately spherical in shape and had rough surface textures. Wheat starch yielded only a single spherical small-particle species. Experimental evidence is consistent with the theory that spherocrystalline particles result from crystalliz- ation of helical inclusion complexes formed from amylose and the native lipid material present in cereal starch granules.

Last Modified: 12/19/2014
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