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United States Department of Agriculture

Agricultural Research Service

Research Project: MODIFICATION OF NATURAL POLYMERS BY THERMO-MECHANICAL PROCESSING

Location: Plant Polymer Research

Title: Effect of Fatty Acid Structure on the Morphology of Spherulites Formed from Jet Cooked Mixtures of Fatty Acids and Defatted Cornstarch

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

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 15, 2006
Publication Date: May 16, 2006
Citation: Fanta, G.F., Felker, F.C., Shogren, R.L., Salch, J. 2006. Effect of fatty acid structure on the morphology of spherulites formed from jet cooked mixtures of fatty acids and defatted cornstarch. Carbohydrate Polymers. 66:60-70.

Interpretive Summary: Crystalline particles are formed when hot, jet cooked dispersions of starch are slowly cooled. These particles result from crystallization of complexes that form from the amylose component of starch and the small amount of lipid material that is normally present in cereal starch granules. Use of these particles for certain applications, for example as biodegradable fillers in plastics, depends upon their size and shape. Although numerous factors can influence particle size and shape, we have observed that the type of particle formed is governed to a large extent by the chemical nature of the lipid material that interacts with starch to form the complex. The knowledge gained in this investigation will thus allow us to tailor the size and shape of these crystalline particles for specific end-use applications.

Technical Abstract: Defatted cornstarch was jet cooked with palmitic acid (free acid and partially neutralized), linoleic acid (free acid and partially neutralized), oleic acid, stearic acid and myristic acid. The different spherulite species formed in these experiments were separated by fractionation and characterized by light microscopy, SEM, X-ray diffraction and lipid content. Although fatty acid structure is an important factor in determining the size and shape of the spherulites formed, variations in the types of spherulites formed were observed with fatty acids having similar chemical structures and also with the same fatty acid under different experimental conditions. The chemical structure of the fatty acid is thus not the only factor controlling spherulite morphology. Variables that can affect the formation and growth of the crystalline lamellae that make up these spherulites are considered.

Last Modified: 4/20/2014
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