Flow Properties and the Velocity through the Pharynx of Solutions Prepared from Commercial Thickening Agents and Those of Yogurt with Relevance to Liquid-Type Care Foods for Dysphagic Patients

Abstract

The viscosity, μ, and the velocity through the pharynx of solutions prepared from commercial thickening agents were compared with “fractured yogurt” as a model bolus of yogurt to evaluate their suitability as care foods for dysphagic patients. From the shape of velocity spectra and the values of velocity, the flow property of the “fractured yogurt” was considered to be close to that of the bolus of yogurt. The value of μ for the yogurt-like thickener solution was smaller than the apparent viscosity, μ_app, for the “fractured yogurt” around the shear rate of 10 s^-1. In addition, the value of V_max, an index for the safety of care foods, for the yogurt-like and jam-like solutions was larger than that for the fractured yogurt. These results indicate that a yogurt-like solution does not necessarily have flow properties similar to those of yogurt and is less safe for dysphagic patients than yogurt.