The Influence of Temperature, Pressure and Shearing Action on the Gelatinization of Starch

Abstract

The operating parameters inside the extruder were devided into temperature, pressure and shearing action. The relationships between the gelatinization of starch and these parameters were investigated. Regardless with the temperature and the kinds of samples, the slopes of these P-Q (pressure-flow rate) curves were found to be about 2.5 when the samples flowed under high temperature and pressure. The gelatinization ratios of low moisture starch samples were 75-80% when they were treated under the conditions of 150°C, 20min and 400kg/cmcm² load in a closed cell. However the gelatinization ratios of the same samples were higher than those obtained under the above conditions by 5-15% when they were pressed out through a die with strong shear force after treating under milder conditions than the above mentioned.