Cereal Chem 58:517 - 520.  |  VIEW ARTICLE
Sorption of Water, Sodium Sulfate, and Water-Soluble Alcohols by Starch Granules in Aqueous Suspension.

J. N. BeMiller and G. W. Pratt. Copyright 1981 by the American Association of Cereal Chemists, Inc. 

A method using blue dextran 2000 to measure the amount of water sorbed by starch granules in suspension is reported. The dextran is too large to penetrate starch granules; therefore, as granules sorb water, the concentration of the dextran increases in the free solution. The concentration change is followed spectrophotometrically. The method was used to determine the sorption of water by various starches and starch derivatives; however, because the chromophore is anionic, the method does not work with cationic starches that adsorb blue dextran. Potato starch and corn starch had water contents of 33 and 28%, respectively, in suspension at neutral pH. Water uptake increased only slightly with increasing pH. Sodium sulfate went into granules with water but did not mix with the tightly bound moisture of the granule. Dimethoxyethane, a hydrophobic molecule, did not penetrate the granules to a significant extent. Methanol, ethanol, 1-propanol, and 1-butanol were preferentially sorbed in comparison to water. They appeared to penetrate the granules with the water and to mix freely with the moisture of the granule. Under conditions of industrial derivatization (high pH, Na2SO4, NaOH), the alcohols were taken up in even larger amounts.