Cereal Chem 65:493-496   |  VIEW ARTICLE

Characterization of Starch Cooked in Alkali by Aqueous High-Performance Size-Exclusion Chromatography.

D. S. Jackson, C. Choto-Owen, R. D. Waniska, and L. W. Rooney. Copyright 1988 by the American Association of Cereal Chemists, Inc. 

Commercial corn starches with different amylose-amylopectin (AMY-AMP) ratios were characterized using aqueous high-performance size-exclusion chromatography (HPLC-SEC). Starch (0.5%) was boiled in water for 10 min, autoclaved for 10 min, sonicated for 20 sec, and centrifuged for 10 min. Molecularly dispersed starch in the supernatant was separated into AMP and AMY using water as the mobile phase. AMP molecules have a wider range of hydrodynamic volumes and apparent molecular weights than do AMY molecules. Boiled and autoclaved starch was not molecularly dispersed in water. After sonication treatment, this cooked starch was molecularly dispersed in water without depolymerization; however, complete molecular dispersion was not achieved. Starch cooked with sodium hydroxide (NaOH) had increased water solubility, but starch was depolymerized or its effective diameter decreased at NaOH concentrations of 0.001N (0.04% w/w) and greater. The AMP HPLC-SEC profile was more affected by sonication, NaOH, and CaO treatments than was AMY. CaO increased solubility and decreased starch apparent molecular weight or effective diameter, at levels as low as 0.005% CaO. An insoluble gel material was observed at 0.08% CaO; it increased with increasing CaO levels. Solubilized starch cooked with CaO consisted mostly of AMP and a starch fraction with an elution volume between AMP and AMY. This aqueous HPLC-SEC technique permits characterization of water-soluble starch in food systems.