OXIDATION OF STARCH BY THERMOCHEMICAL PROCESSING

The oxidation of starches of different amylose content with several ox idants has been investigated to maximize carboxyl content, increase wa ter solubility and give products with new and novel properties. Method s of preparation studied were ambient-batch, jet cooking, jet cooking- drum drying, and drum drying alone. Other variables evaluated were rea ction pH, jet cooking temperature, and oxidant concentration. Hypochlo rite was the most effective oxidant and gave the highest carboxyl cont ent in all preparation methods. Oxidized starches prepared by jet cook ing and/or drum drying were of low viscosity and water soluble. SEM's of commercial oxidized starch showed intact granular structure, wherea s samples prepared by instantaneous high temperature procedures showed complete gelatinization. Gel permeation chromatography showed structu ral depolymerization of the starches when high temperature processing was used. Copper binding capacity was evaluated on selected samples.