Cereal Chem 63:89-92   |  VIEW ARTICLE
A Simplified Colorimetric Procedure for Determination of Amylose in Maize Starches.

C. A. Knutson. Copyright 1986 by the American Association of Cereal Chemists, Inc. 

When iodine is dissolved in mixtures of water and dimethylsulfoxide (Me2SO), triiodide ion is formed; the extent of triiodide formation is dependent upon the proportion of Me2SO in the mixture. A method has been developed to utilize this reaction to form the blue amylose-iodine complex, providing a simple procedure for quantitative measurement of amylose in starches. Starch is dissolved in a mixture of 90% Me2SO and 10% water containing iodine. Upon dissolution of the starch, the mixture is diluted with water to give a final Me2SO concentration of 10%, whereupon the blue amylose-iodine complex forms immediately. Amylose is then determined by measurement of the absorbance of the complex at 600 nm. Use of Me2SO to generate triiodide ion eliminates the necessity for preparing buffered solutions of iodine in potassium iodide. Accuracy and sensitivity of the procedure is equivalent to that of the conventional methods of preparing the amylose-iodine complex.