OXIDATION OF MAIZE AND RICE STARCHES USING POTASSIUM-PERMANGANATE WITH VARIOUS REDUCTANTS

Maize and rice starches were independently treated with potassium perm anganate in presence of the reductants citric acid, oxalic acid and so dium sulphite under various conditions of pH, temperature, time, liquo r ratio and permanganate concentration. The treated starch samples wer e monitored for carboxyl and carbonyl contents as well as apparent vis cosity at various rates of shear. This treatment yields mixed type oxi dized starch because it contains both carboxyl and carbonyl groups, th e amounts depending upon the conditions. The apparent viscosity of the starch decreases on oxidation, the rate increasing with increase in r ate of shear. Maize starch is more susceptible to oxidation than rice starch. When applied as sizing agents for cotton textiles, oxidized st arches display a better performance than the unoxidized starch.