2012 Volume 45 Issue 2 Pages 104-114
We investigated the effects of thickener concentration on mastication and swallowing by measuring the apparent viscosity and pharyngeal bolus transit velocity of solids dispersed in a sol. The apparent viscosity of a sol sample with added potato starch (PS) was almost equivalent to that of samples with added water, regardless of the sol concentration. The apparent viscosity of sol samples with added guar gum (GG) and xanthan gum (XG) was affected by mastication when the sol concentration was low (the apparent viscosity was increased) but the effect of solids was weak for samples with a high sol concentration. The effect of sol concentration on the pharyngeal bolus transit velocity of the PS sample was weak; however, the maximum transit velocity of the GG and XG samples tended to decrease with increasing sol concentration. The relationship between the intra-oral shear rate and shear stress revealed that PS had a high shear rate but low shear stress, while GG and XG had a low shear rate and high shear stress. A narrower range of bolus shear rate was indicated in the pharynx than in the oral cavity, although the range of pharyngeal shear stress was wider.
