Heating-cooling extrusion cycles as a method to improve the physicochemical properties of extruded corn starch

Abstract

This work proposed a controlled method to modify the physicochemical properties of corn starch through heating and cooling extrusion (HCE) cycles. It was used native corn starch adjusted to 60% moisture. It was then subjected to 5 HCE cycles at 100 and 125 °C, at 10 rpm. Water absorption index (WAI), water solubility index (WSI), resistant starch (RS), thermal properties, viscosity, FTIR, and X-ray were evaluated. For WAI and WSI, a gradual increase was observed on each HCE cycle. Thermal properties shown that enthalpy decrease with each HCE cycles due to more gelatinization. Viscosity properties shown a thermally stable starch conditions being directly proportional to HCE cycles. The RS increased for each 5 HCE. XRD revealed that HCE cycle changed the starch structure from an orthorhombic structure to V-type crystalline structure. Finally, it was concluded that HCE cycles is a method to produce corn starch with controlled physicochemical properties.

Keywords: Corn starch; Crystalline structure; Extrusion.