Cationization of potato and tapioca starches using an aqueous alcoholic-alkaline process

Cationization of native starches is normally conducted in aqueous alkaline suspensions that require high concentrations of salts to control granule sw elling and gelatinization. Native potato and tapioca starches were cationiz ed with 3-chloro-2-hydroxypropyltrimethyl ammonium chloride to IDS 0.04 in an aqueous alcoholic-alkaline solvent in 3 h and 4 h, respectively, and the re was no need for extensive washing of starch to remove the salts that als o represented an effluent disposal problem. The cationization times to reac h DS 0.04 in the aqueous (65 %) ethanol solvent could be reduced to 1.5-2 h by increasing the alkaline concentration from 2.8 M to 3.6 M NaOH but the reaction temperature of 50 degrees C gave the most stable reaction rates. T he cationized potato and tapioca starches exhibited markedly reduced pastin g temperatures of 46.5 degrees C and, while a higher peak viscosity was rec orded for potato starch, tapioca starch exhibited a low viscosity throughou t the heating and cooling cycle on the amylograph.