Abstract
The effects of sodium chloride (NaCl) on the rheological properties of corn starch paste samples were studied by steady and dynamic viscoelasticity measurements, DSC measurements, and microscopic observation. The concentration of NaCl was varied between 0 and 25 wt%. The viscosity of the pastes in the presence of NaCl underwent a variable change according to the NaCl concentration. The effect of increasing the viscosity of the pastes was enhanced with NaCl concentrations below 5 wt%and above 15 wt%. When Cl- could penetrate the starch granules, the hydrogen bonds were ruptured and then the viscosity increased. However, the gelatinization temperature was sifted higher and the enthalpy increased with increasing NaCl concentration up to 10 wt%. The viscosity of the starch pastes with intermediate NaCl concentrations (between 5 and 15 wt%) therefore decreased, because swelling of the starch granules was prevented and complete gelatinization did not occur.
