Yield stress components of waxy corn starch-xanthan mixtures: Effect of xanthan concentration and different starches
2006
Achayuthakan, P. | Suphantharika, M. | Rao, M.A.
Yield stress of 6% (w/w) waxy maize (WXM), cross-linked waxy maize (CLWM), and cold water swelling (CWS) starches in xanthan gum dispersions: 0%, 0.35%, 0.50%, 0.70%, and 1.0% was measured with the vane method at an apparent shear rate of 0.05 s-1. The intrinsic viscosity of the xanthan gum was determined to be: 112.3 dL/g in distilled water at 25 °C. Values of the static (σs0s) and dynamic (σs0d) yield stress of each dispersion were measured before and after breaking down its structure under continuous shear, respectively. The WXM and CWS starches exhibited synergistic behavior, whereas the CLWM starch showed antagonistic effect with xanthan gum. The difference (σs0s - σs0d) was the stress required to break the inter-particle bonding (σsb). The contributions of the viscous (σsv) and network (σsn) components were estimated from an energy balance model. In general, values of σsb of the starch-xanthan gum dispersions decreased and those of σsn increased with increase in xanthan gum concentration.
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