Effect of hydrothermal treatment on the physical and rheological properties of maize starches

Standard maize (SMS) and waxy maize starch (WMS) were hydrothermally treated at their residual moisture level (similar to 12%) by Instantaneous Controlled Pressure Drop process in order to obtain pre-gelatinised starches in a single step. The effects of two parameters of this process, namely the steam pressure level and processing time, on the structural and rheological properties of the native maize starches were described. The occurrence of partial gelatinization for DIC treated starches was clearly attested by the increase of the median volume diameter in cold water, the decrease of the gelatinization enthalpy and a loss of birefringence under polarized light. This was more prominent for the highest pressure and longest time: 2.7-3 bar for 200-300 s. Sensitivity of starches to the process was also dependent on their origin, SMS being more affected than WMS. (c) 2005 Elsevier Ltd. All rights reserved.