Abstract
The effects of guar gum (GG) and xanthan gum (XG) at different concentrations (0, 0.2, 0.4, and 0.6% w/w) on the rheological properties of Korean waxy rice starch (WRS) pastes were evaluated under both steady and dynamic shear conditions. The flow properties of WRS-gum mixtures were determined from the rheological parameters of the power law model. The addition of GG and XG to WRS resulted in an increase in the apparent viscosity (νa,100) and consistency index (K) values obtained from power law model. The flow behavior index (n) values of the WRS-XG mixtures decreased with an increase in gum concentration while there was only a marginal difference between n values for the WRS-GG mixtures. Dynamic moduli (G', G", and νz.ast;) values in the WRS-gum mixture systems also increased with an increase in gum concentration. WRS-XG mixtures had higher dynamic moduli and lower tan δ (ratio of G"/G') values than WRS-GG mixtures, indicating that the higher dynamic rheological properties of WRS-XG can be attributed to an increase in the viscoelasticity of the continuous phase in the starch-gum mixture systems, which was due to the higher viscoleastic properties of XG compared to GG. The dynamic (νz.ast;) and steady shear (νa) viscosities of the WRS-XG paste at a 0.2% gum concentration followed the Cox-Merz superposition rule.
Original language | English |
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Pages (from-to) | 233-239 |
Number of pages | 7 |
Journal | Journal of Food Science and Nutrition |
Volume | 14 |
Issue number | 3 |
DOIs | |
State | Published - 2009 |
Keywords
- Cox-Merz rule
- Dynamic moduli
- Guar gum
- Rheology
- Waxy rice starch
- Xanthan gum