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The purpose of this paper was to examine the rheological characterisation of thickened water under different temperature and pH conditions and thickened milk with different fat contents.

Beverages thickened with powdered thickeners are used in the medical management of individuals who suffer swallowing difficulties (dysphagia). Each individual requires a specific level of thickness to best meet the needs of their dysphagia. Although the level of thickness is defined, obtaining the correct consistency of thickened fluids is difficult. This is due to fluctuations associated with temperature and type of fluids to be thickened. Rheological characterisation of commercially available xanthan gum-based thickener was performed under different conditions of temperature, pH and fat contents.

The viscosity and the yield stress of thickened water was found to be unaffected by pH. Similarly, temperature did not affect the viscosity at a high thickener concentration, although it did at lower concentration levels. Conversely, viscosity and yield stress increased as fat levels increased in thickened milk. Furthermore, thickened water took less than 2 minutes to reach equilibrium viscosity, while thickened milk required approximately 15 minutes to reach equilibrium viscosity.

These findings have implications for the standing time required for different beverages before they are thickened to a consistency that has been deemed safe for the patient’s physiological needs. Additionally, it highlights that different liquid base substances required different amounts of thickener to achieve the same level of thickness.

Findings from this study confirms and explores the variability of thickened fluids under different conditions of temperature, pH and fat content for the medical management of dysphagia.