Structure formation in extrusion-cooked starch-sucrose mixtures by carbon dioxide injection

Abstract

Carbon dioxide injection into an extrusion cooker is able to produce structured extrudates under low-temperature and high-moisture conditions when the release of steam does not contribute. The effect of carbon dioxide injection pressure on the extruder response and the resulting extrudate structure was studied for wheat starch-sucrose mixtures. An increase in gas pressure decreased the pressure gradient in the extruder and the die pressure, although it had a relatively small effect on the specific mechanical energy consumption. The degree of expansion reached a maximum (and the density a minimum) with increasing gas injection pressure for each composition for the extrusion conditions studied.