OXIDATION OF STARCH BY THERMOCHEMICAL PROCESSING

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