Rheological properties of heated cross-linked waxy maize starch dispersions

The effect of starch concentration on time-dependent, steady shear, and dynamic shear rheological properties of heated cross-linked waxy maize starch (CWM) starch dispersions was studied. The influence of storage time at 5°C on the rheological properties, the applicability of the Cox-Merz rule, and the sol-gel transition of a 5% (w/w) were also examined. The heated CWM starch dispersions exhibited antithixotropic and shear-thinning with yield stress behaviors. The former behavior increased with both starch concentration and shear rate between 100s^-1 and 400s^-1. As expected, the apparent viscosity at a fixed shear rate and the yield stress increased with starch concentration. Because the Cox-Merz rule was not applicable, the dispersions may be classified as weak gels. Both differential scanning, calorimetry and thermorheological data showed that the onset of starch gelatinization temperature was 63°C.