MODIFICATION OF NATURAL POLYMERS BY THERMO-MECHANICAL PROCESSING
Location: Plant Polymer Research
Title: CRYSTALLINE PARTICLES FORMED IN SLOWLY-COOLED CORNSTARCH DISPERSIONS PREPARED BY STEAM JET COOKING. THE EFFECT OF STARCH CONCENTRATION, ADDED OIL AND RATE OF COOLING.
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 4, 2005
Publication Date: October 1, 2005
Citation: Fanta, G.F., Felker, F.C., Shogren, R.L., Byars, J.A., Salch, J. 2005.Crystalline particles formed in slowly-cooled cornstarch dispersions prepared by steam jet cooking. The effect of starch concentration, added oil and rate of cooling. Carbohydrate Polymers. 61(2):222-230.
Interpretive Summary: Crystalline particles are formed when hot, jet cooked dispersions of starch are slowly cooled. These particles result from crystallization of complexes formed from the amylose component of starch and the native lipid materials normally present in cereal starch granules. The size and shape of the particles observed in these cooled dispersions depends upon the concentration of starch, the rate at which the jet cooked dispersions are cooled, and whether or not mineral oil is added to the starch dispersion prior to steam jet cooking. End-use applications for these particles are currently being investigated. Determination of the effects of processing variables on the nature of the particles formed allows us to tailor the size and shape of these crystalline particles for specific applications. This work will benefit farmers by creating new markets for surplus starch.
Spherical/lobed and torus-shaped particles were formed when cornstarch dispersions, jet cooked in the absence of oil at 4-10% starch solids, were slowly cooled for 22 h. In the presence of mineral oil, the torus-shaped particles were replaced with small spherical particles that resembled those formed from wheat starch in the absence of oil. Dispersions cooled for 4 h in the absence of oil also yielded these small spheres, in addition to the spherical/lobed and torus-shaped particles. With 4 h cooling in the presence of oil, no torus-shaped particles were formed, and the 1-2 micro spheres were the only small particles observed. With 4% and 5% starch, few, if any, spherical/lobed particles were formed with 4 h cooling in the presence of oil. Explanations for the effects of oil droplets and cooling rate on the nature of the particles formed were presented.