Preparation of oxidized corn starch in a screw extruder under alkali‐free conditions

Abstract

AbstractTo promote water solubility of oxidized starch prepared by the dry process, a twin screw extruder was used as a reactor in the present study. Through single‐factor experiments and orthogonal experiment, the effects of barrel temperature, moisture content, addition amount of NaOCl, and screw speed on the carboxyl content (CC) and water solubility index (WSI) of oxidized corn starch were investigated. The results indicated that high screw speed, medium barrel temperature, and low moisture content could lead to high WSI of oxidized corn starch produced by extrusion. The reaction efficiency and solubility of oxidized starch prepared by reactive extrusion under the optimal condition were all improved greatly, especially the WSI was very high (99.56%). Preparation of oxidized starch by reactive extrusion under alkali‐free conditions could be described as a rapid (only several minutes), continuous, reduced addition amount of NaOCl, eco‐friendly new dry technology.