Cereal Chem 66:173-182   |  VIEW ARTICLE

Starch Paste Clarity.

S. A. S. Craig, C. C. Maningat, P. A. Seib, and R. C. Hoseney. Copyright 1989 by the American Association of Cereal Chemists, Inc. 

The visual characteristics of aqueous starch pastes from various sources were investigated. Whiteness of a starch paste was determined visually against a black background, and clarity was judged by the sharpness and intensity of an object viewed through the paste. Light transmittance of native and modified starch pastes were determined as well as some effects of sucrose, lipids, salts, and solvents. From these series of experiments, starch pastes were classified into three categories depending on their behavior in light: 1) high clarity and almost no whiteness, which we propose is due to little or no refraction of light because of a lack of swollen granular remnants, and little reflection of light (starch molecules have an extended and stable conformation due to inter- and intrachain repulsion with limited association of starch chains); 2) moderate clarity and high whiteness, due to little refraction (few granular remnants) and high reflection of light (starch molecules have a collapsed conformation due to interchain association, which might lead to significant association of starch molecules); 3) low clarity and low whiteness, due to high refraction of light by swollen granular remnants, but little reflection of light by collapsed or associated starch molecules.