Cereal Chem 38:251 - 255.  |  VIEW ARTICLE

Characterization of Intermediary Fractions of High-Amylose Corn Starches.

R. L. Whistler and W. M. Doane. Copyright 1961 by the American Association of Cereal Chemists, Inc. 

Starches from high-amylose corn of du su2, ae su1, ae ae types, and from commercial corn have been shown to possess a fraction intermediate between amylose and amylopectin, which has been isolated in yields of 8.7, 7.5, 6.6, and 4.5%, respectively. Separation is effected by fractionating out the amylose as either the 1- butanol or 1-nitropropane complex and then precipitating the intermediate fraction from the supernatant with 2-nitropropane. Intermediate fractions from these different starches are similar in iodine color, iodine blue value, iodine sorptive capacity, optical rotation, and rate of retrogradation. Those from the high- amylose starches have much lower viscosities and have possibly lower molecular weights than the fraction from commercial corn. All properties suggest that the intermediate fractions contain less highly branched molecules than does amylopectin and that the molecules are intermediate in shape between amylose and amylopectin.