High-solid systems of partially hydrolysed waxy maize starch: rheological and structural characterisations
The rheological behaviour of some high-solid mixed dispersions of partially hydrolysed waxy maize starch (HWS), in the presence of whey protein concentrate (WPC) and urea, was followed by small-amplitude oscillatory measurements in the linear domain, under heating to 80 °C and cooling to 25 °C, at pH 7.5. The non-gelling HWS sample was obtained by sonication of previously gelatinised waxy maize starch. Steady-shear flow and microstructure were investigated after cooling to 25 °C. Dispersions were prepared at 1:1 (m/m) WPC/urea ratio, with increasing HWS concentrations. Typical solid- and liquid-like rheological behaviours were observed after quenching the mixtures to low temperature, depending on HWS/WPC ratio. At the lowest HWS/WPC ratio, a thixotropic structure was characterised under steady-shear flow, and visualised by light microscopy at low magnification as a continuous network. With increasing HWS/WPC ratio within a certain range, gelling and non-gelling mixtures resulted in phase-separated structures, which hindered viscous flow. At the highest HWS/WPC ratio, a shear-thinning dispersion was formed, consistent with the liquid-like small deformation properties and the homogeneous image obtained by light microscopy.
| Main Authors: | , , , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedade Brasileira de Química
2007
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| Online Access: | http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532007000100007 |
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