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 degrees 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 thermo-rheological data showed that the onset of starch gelatinization temperature was 63 degrees C.