Cereal Chem 41:406 - 411.  |  VIEW ARTICLE

Influence of Preparative Variables on Intrinsic Viscosities and Sedimentation Values of Periodate-Oxidized Starches.

W. C. Schaefer, R. C. Burr, C. R. Russell, G. E. Babcock, and C. E. Rist. Copyright 1964 by the American Association of Cereal Chemists, Inc. 

A study was made on the effects of reaction conditions and isolation techniques on solution properties of periodate-oxidized corn starch having from 5 to 96% of the anhydroglucose units oxidized to the dialdehyde structure. Samples were prepared for viscosity and ultracentrifugal studies by dispersion in 0.5N potassium hydroxide containing 25% (w/v) urea after the aldehyde groups were reduced with potassium borohydride to the corresponding primary alcohols. The polyol thus formed is stable toward alkali. On the basis of measurements of solubility, sedimentation velocity, and intrinsic viscosity, the effects of preparative variables on particle size may be summarized thus: Cross-linking occurred during oxidation of granular starch and was most extensive at intermediate levels of oxidation. More cross-linking occurred at a reaction temperature of 35 C. than at 1 C. Less cross-linking occurred during oxidation of pasted starch than of granular starch. Drying at 105 C. instead of at room temperature caused little degradation. Granular, 96%-oxidized starch became cross-linked when treated at pH's less than 4, but degraded at higher pH's. This degradation was shown to reduce the efficacy of oxidized starch as a wet-strength additive in paper.