Cereal Chem 60:116 - 121. | VIEW
Apparent Viscosities of Dispersions of Swollen Cornstarch Granules.
D. D. Christianson and E. B. Bagley. Copyright 1983 by the American Association of Cereal Chemists, Inc.
Cornstarch granules were dispersed in water at various concentrations and heated to 65, 67, 70, 75, and 80 C for various times. Viscosity shear-rate plots for these dispersions were then determined at 60 C and a shear-rate range of 3-500 sec-1 using a rotational viscometer. A variety of viscosity shear-rate curves were observed that varied with concentration, cooking temperature, and cooking time. A very sharp transition in the apparent viscosity behavior occurred between 65 and 67 C with, for example, a viscosity of 2,000 cp observed both at 26% concentration when cooked at 65 C for 15 min and at 15% concentration when cooked at 67 C for 15 min. All apparent viscosity-concentration plots for temperatures from 65 to 80 C could be superimposed by plotting eta/CQ vs CQ, where eta is the viscosity, C is the concentration in grams of dry starch per grams of dispersion, and Q is the grams of swollen starch divided by grams of dry starch. The quantity CQ is equivalent to volume fraction of swollen starch in the dispersions.