GELATINIZATION BEHAVIOR OF WHEAT-STARCH I N A TWIN-SCREW MIXER

Native starch with something additives such as distilled water and gly cerin can be gelatinized in a twin screw mixer. The degree of starch g elatinization depends on residence time, temperature, pressure, speed of rotation and concentration of additives. This paper shows that the samples of starch were prepared at concentrations of 20, 30 and 40% of destilled water in a plastograph. Then the degree of starch gelatiniz ation was determined by means of Differential Scanning Calorimetry (DS C). The results show that the degree of starch gelatinization increase s greatly with the increase of residence time and specific mechanical energy at the beginning of the experiment. And then it increases slowl y until reaching 100%. On the other hand the increase of destilled wat er slows down the gelatinization. In order to describe the gelatinizat ion process a mathematical model is found. The calculated degree of ge latinization agrees with the experimental results.