Rheological behavior of cross-linked waxy maize starch dispersions during and after heating
A model was developed to describe the complex viscosity versus temperature (Î·∗–T) data on 5% (w/w) cross-linked waxy maize (CWM) starch dispersions (STDs) obtained over the frequency range (Ï) 1.26–31.38 rad s−1 and temperature range 55–95°C. The 5% CWM starch dispersions had an onset gelatinization temperature at 60°C with a peak complex viscosity of 6.9 Pa s at 64°C. The lowest post-gelatinization complex viscosity (Î·∗) was about at 80°C. The complex viscosity was related to the apparent viscosity using a Modified Cox–Merz rule. Flow tests on gelatinized 5% CWM STDs showed that the sample exhibited a combined time-dependent shear-thickening (antithixotropic) and time-dependent shear-thinning (thixotropic) behavior. The antithixotropic behavior, that appears to have resulted from a shear-induced structure formation, predominated when the level of shear stress imposed on the sample was less than 120–150 Pa.