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Rheological Properties of Dispersions of Spherulites from Jet-Cooked High-Amylose Corn Starch and Fatty Acids

¹Cereal Products and Food Science Research Unit, National Center for Agricultural Utilization Research, ARS, USDA, 1815 N University St., Peoria, IL 61604. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. ²Corresponding author. Phone: +1 309 681 6330. Fax: +1 309 681 6685. E-mail: jeffrey.byars@ars.usda.gov ³Plant Polymer Research Unit, National Center for Agricultural Utilization Research, ARS, USDA, 1815 N University St., Peoria, IL 61604.

High-amylose corn starch was cooked in an excess-steam jet cooker in the presence of 5% oleic or palmitic acid, based on amylose. The cooked product was rapidly cooled in an ice bath and then freeze-dried or drum-dried. Amylose was removed from solution by forming helical inclusion complexes with the fatty acid, and the inclusion complexes formed submicron spherical particles upon cooling. The dried material was reconstituted to form a paste that exhibited gel-like properties upon standing, but that flowed readily when shear was applied. The rheological properties of these pastes were measured to determine the effects on the flow properties of 1) the solids concentration in the reconstituted paste, 2) the method of sample drying and reconstitution, and 3) the fatty acid used. The materials were very spreadable, and at the highest concentrations their flow properties were similar to a commercial shortening. The pasting properties of the dried solids were also examined.