2007 Volume 19 Issue 1 Pages 23-30
Swallowing disorder is becoming a serious issue with increasing in elderly people, because pneumonia caused by aspiration is often the death of the aged.An increase in liquid food viscosity is effective to protect the aspiration, and thus a lot of thickener additives are used to raise the viscosity of drinks or liquid care foods. However, there is not a viscometer, which is easy to use in a kitchen. A cook has to adjust the viscosity by intuition for the people with swallowing disorder. We characterized the viscous property of care foods liquefied with a blender, thickener solutions, and contrast mediums with thickener. Based on those viscous characteristics, a new handheld viscometer was developed. This rotational-type viscometer enabled to define a shear rate. This function is essential, because almost all the liquid foods are non-Newtonian fluids. The developed handheld viscometer was calibrated using Newtonian fluids, the viscosities of which were known. It was found that the viscometer had enough accuracy and repeatability in the viscosity measurement. The trial handheld viscometer was applied to the viscosity measurement of liquid foods, and a reasonable agreement was obtained with the rheometer's results.In addition, we investigated the influence of food temperature and the temporal change in food viscosity, and proposed the guidelines for the practical use.
