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United States Department of Agriculture

Agricultural Research Service

Title: Phase Separation and Shear-Induced Aggregate Formation in Starch Solutions.

Authors
item Kim, Sanghoon
item Xu, Jingyuan
item Carriere, Craig
item Willett, Julious

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 12, 2003
Publication Date: September 25, 2003
Citation: Kim, S., Xu, J., Carriere, C.J., Willett, J.L. 2003. PHASE SEPARATION AND SHEAR-INDUCED AGGREGATE FORMATION IN STARCH SOLUTIONS.. Meeting Abstract. xx.

Technical Abstract: Starches are composed of two components, branched carbohydrate with high molar mass amylopectin and linear carbohydrate with lower molar mass amylose. Conventionally, fractionation of the two components has been achieved by aqueous dispersion or aqueous leaching of granules, and selective retrogradation or alcohol precipitation of one component from starch dispersion. We found that starch solutions show phase separation provided that the concentration of starch, temperature, and solvent medium are properly chosen. In general, starch solutions behave in the same way as a pseudo-binary system like a synthetic polymer solution, polystyrene/poly(butadiene)/dioctylphthalate and show upper critical solution temperature behavior. The construction of phase diagram provides us with a new simple method for isolating amylose from starch solutions. For demonstration, two phase diagrams, one for native potato starch and the other for waxy starch and isolated amylose, were shown. As shear fields were applied to the starch solution, shear-induced aggregate formation was observed at higher than ca.100 s-1. This behavior was investigated with a custom-built shear microscope and a rheometer. It was found that the aggregates are formed as functions of shear rate and time.

Last Modified: 9/23/2014
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