Abstract
Rheological properties of rice starch-xanthan gum mixtures (5% w/w) at different xanthan gum concentrations (0%, 0.2%, 0.4%, 0.6%, and 0.8% w/w) were evaluated in steady and dynamic shear. The rice starch-xanthan gum mixtures at 25 °C showed high shear-thinning flow behavior (n = 0.13-0.24), and consistency index (K) and apparent viscosities (ηa,100) increased with the increase in xanthan gum concentration. In the temperature range of 25-70 °C, mixtures followed the Arrhenius temperature relationship. Activation energy (1.83-9.89 kJ/mol) decreased and storage (G′) and loss (G″) moduli increased with the increase in xanthan gum concentration. The dynamic (η*) and steady shear (ηa) viscosities at several xanthan gum concentrations followed the Cox-Merz superposition rule with the application of shift factor (α). Magnitudes of shift factor were in the range of 0.307-0.478. During aging at 4 °C for 10 h, the values of G′ were found to increase rapidly the early stage and attained the plateau region after a few hours. The increase in rate constant (k) in gelation of rice starch-xanthan gum mixtures was a function of xanthan gum concentration.
Original language | English |
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Pages (from-to) | 120-128 |
Number of pages | 9 |
Journal | Journal of Food Engineering |
Volume | 75 |
Issue number | 1 |
DOIs | |
State | Published - Jul 2006 |
Keywords
- Dynamic property
- Gelation
- Rheology
- Rice starch
- Xanthan gum