Small-deformation rheology investigation of rehydrated cell wall particles–xanthan mixtures

Abstract

The rheological behaviour and microstructural properties of rehydrated cell wall particle (CWP) dispersions and CWP–xanthan mixtures were investigated using small-deformation rheology and confocal laser scanning microscopy. Dispersions with two different CWP particle sizes were used. CWP dispersions were found to be elastic with a weak-gel type behaviour. The elastic modulus was a function of the CWP concentration c p and depended on the particle size of the CWP. The addition of xanthan to the CWP dispersions was found to affect the rheological behaviour of the CWP–xanthan mixtures at low CWP concentration ( c p ≤ 1 wt%), due to the increase in the viscoelastic properties of the continuous phase. At high CWP concentrations ( c p ≥ 3%), the effect of xanthan on the rheological behaviour of the CWP–xanthan mixtures was marginal, as the viscoelastic behaviour of the mixtures was dominated by the CWP particle network, with xanthan molecules entrapped in the interstitial voids. However, at intermediate CWP volume fractions (e.g. at a CWP concentration c p = 2%) both xanthan and CWP phases contributed to the viscoelastic behaviour of the CWP–xanthan mixtures.