Microwave assisted chemical modification of starch in presence or absence of amylase enzyme and its application in textile printing

Abstract

The main aim of the current work is to investigate the influences of microwave irradiation (in absence of α-amylase enzyme) on the properties of different kinds of starches namely maize (MS), rice (RS), and wheat starch (WS). To achieve this goal. Starch was subjected to microwave irradiation in the absence of enzyme namely α-amylase under different conditions. The latter comprise is the starch concentration, time, and temperature of microwave irradiation. Furthermore, starch was subjected to microwave irradiation in the presence of enzyme under different conditions too. The latter comprises the concentration of enzyme and power level (watt) of microwave irradiation. The influence of these treatments on both the solubility as well as rheological properties of treated starches was thoroughly evaluated. Moreover, the visibility of using these treated starches as a thickening agent in burn-out printing style in printing paste was also investigated. The results of these investigations demonstrated that the optimum condition was found to be 10g starch (irrespective of the starch nature) in 100 ml water at pH 7 then added 0.2 ml of α-amylase enzyme. The mixture was cured at 55 • C for 3 minutes at 30 watts under microwave irradiation. Also, the obtained result showed that at a constant rate of shear the apparent viscosity increases by increasing the concentration of starch, temperature as well as time of treatment, irradiation of starches in presence of enzyme convert the rheological properties of starches from non-Newtonian thixotropic into non-Newtonian pseudoplastic. The prepared pastes were successfully used in printing wool/polyester (45/55) or wool/nylon (70/30). Where the loss in weight of the burn-out printed wool/polyester or wool/nylon is slightly higher on using modified starches compared with mypro gum. The color fastness of printed sample for rubbing, washing and perspiration was evaluated.