Cereal Chem 44:118 - 128.  |  VIEW ARTICLE
Heterogeneous Reaction of Granular Starch with Hydrogen Chloride. II. Quantitative Studies.

T. R. Thomson and S. D. Parks. Copyright 1967 by the American Association of Cereal Chemists, Inc. 

Quantitative studies were made on the reaction of dry, granular starch with anhydrous hydrogen chloride gas. The weight, chemical analysis, and cold-water solubility of the products were determined as a function of time of reaction; the water extracts were examined on the same basis. The reaction is easily followed by pressure measurements in a simple Warburg-type apparatus which clearly indicates both the rate and the induction period, as there is a sudden change in rate at the end of the latter. Different starches, such as rice, corn, wheat, and potato, had different rates and induction periods, indicating that granule size and structure play a major role in the kinetics. It appears possible to characterize starches, to a certain extent, with this reaction. The reaction appears to be one of diffusion into and disorganization of the granule by the HCl during the induction period, followed by a dehydration reaction; the result is a black, inert, water-insoluble, granular product that appears to be cross-linked.