Hide/Show Apps

Anti-thixotropic properties of waxy maize starch dispersions with different pasting conditions

2010-03-17
Wang, Bao
Li, Dong
Wang, Li-Jun
Özkan, Necati
The effects of pasting conditions, testing temperature, and shear rate on the anti-thixotropy of waxy maize starch (WMS) dispersions were investigated in this study. Activation energy and viscoelastic properties of the WMS dispersions were also determined to understand the anti-thixotropy of these dispersions. The WMS dispersions (5.0 wt.%) displayed both thixotropic and anti-thixotropic properties in loop and shear recovery tests, depending on pasting conditions and testing temperature. The standard anti-thixotropy test indicated anti-thixotropy of WMS dispersions only appeared at a certain shear rate range. When WMS dispersion was pasted more completely, the shear rate range for anti-thixotropy became wider, also the sample showed improved heat stability. The anti-thixotropy of the WMS dispersions was ascribed to re-range of the amylopectin molecules under appropriate shear rates. The normal maize starch (NMS) dispersion (5.0 wt.%) could not display anti-thixotropy here, due to a different paste structure formed by amylose in the continuous phase.