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Rheological Properties of Starch-Oil Composites with High Oil-to-Starch Ratios

¹Functional Foods 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.

Many applications have been developed for aqueous dispersions of jet-cooked starch-oil composites prepared by excess steam jet cooking. Previous formulations have typically contained 20–50% oil by weight based on the weight of starch. To expand the range of potential applications, new preparation methods were investigated to increase the oil content to as high as four times the weight of starch. High-amylose corn starch was cooked in an excess-steam jet cooker in the presence of oleic acid, and soybean oil was added to form the starch-oil composites. Amylose is removed from solution by forming helical inclusion complexes with the oleic acid and, if the materials are cooled sufficiently quickly, the helical inclusion complexes only form small aggregates and shells around the oil droplets. Depending on the composition and preparation method, a wide range of stable, high-oil materials from low-viscosity liquids to smooth pastes can be formed. The flow, textural, and structural properties of these materials are shown. The materials can be used in a wide range of applications, including spray lubricants, lotions, and for fat delivery in cake mixes.