Effect of enzymatic treatment of starch gelatinized with urea

Abstract

The present work is undertaken with a view to discover the effect of enzymatic hydrolysis using α-amylase enzyme on different kinds of starches. This was done while starch was in the gelatinized form under the action of urea at room temperature. To achieve this goal, maize starch was subjected to gelatinization using urea at room temperature under different conditions. The latter comprise, starch concentration, urea concentration, pH value, time and temperature as well as the concentration of α-amylase enzyme. The modified starches were evaluated via measuring the solubility and the apparent viscosity at various rates of shear. The modified starches were evaluated as thickeners in printing wool fabrics with acid dye and polyester using disperse dye. The results of these investigations demonstrated that the concentration of starch increases from 30 to 40 to 50g%, the apparent viscosity increases regularly irrespective of the rate of shear. The apparent viscosity increases by increasing the amount of urea. Increasing of α-amylase enzyme concentration is accompanied by a decrease in the apparent viscosity at any specific rate of shear. The most suitable pH for starch modification by enzyme was found at pH 7.The temperature highly influences the apparent viscosity of maize starch at any specific rate of shear. However 80◦C can be considered as the optimum temperature in enzymatic modification of maize starch to obtain soluble starch which acquire a suitable viscosity. Generally speaking enzymatic treated starches give better results in direct printing when compared with Daico-thic or mypro gum.