Analysis of flow field of the preparation of solid caramel pigment by extrusion

The producing mechanism of the preparation of caramel pigment by screw extrusion was analyzed. By using the Mesh Superposition Technique provided by the package POLYFLOW the three-dimensional isothermal flows were simulated in the screws of the melt pumping section. Distribution laws of pressure, velocity, viscosity and shear rate of the flow domain in the process of preparation of caramel pigment were analyzed in order to understand the extrusion processing and provide reference for the optimization of screw extruder. The technology and processing parameters for the preparation of solid caramel pigment by extrusion from saccharose were discussed. Effects of the changes in the rotate speed of the screws and barrel temperature on the tinctorial power of caramel pigment were studied. Tinctorial power increased firstly, and then decreased with the increase of the rotate speed, while the tinctorial power increased with the increase of the barrel temperature.