Transformation of native starch into V-type granular starch through ethanol-aqueous heat treatment and its swelling behavior in cold water

Abstract

The poor hydrophilicity of raw starch limits its applications, resulting in increased processing complexity. Ethanol-induced V-type granular starch (EVGS), a type of cold-water swelling starch, can be prepared through ethanol-aqueous heat treatment (EAHT). Four types of native starch with three crystalline structures were used to prepare EVGS. At 70 % ethanol, the preparation process was divided into temperature gradients to explore the EVGS formation process. X-ray diffraction (XRD), DSC (Differential Scanning Calorimetry) and non-isothermal kinetics analysis revealed three stages in the formation process: destruction of the native crystalline structure, formation of composite crystalline structure, and complete formation of V-type crystalline structure. The observed “blocklets” structure of EVGS suggested that the crystalline structure transformation might be based on this structural unit. A water phase gradient dispersion method was used to monitor the cold-water swelling behavior of EVGS: as the dispersion time increased, short-chain amylose leached first, followed by long-chain amylose, accompanied by the enhanced hydrophilicity of amylopectin, the “blocklets” structure limited EVGS swelling extent and prevented complete granules rupture, contributing to its cold paste stability. Overall, this study further elucidated the formation process and the multi-scale structure of EVGS and proposed an interpretation of cold-water swelling process for EVGS.