Examining rheological characteristics and suitability of a tara gum-based commercial thickener at selected international dysphagia diet standardization initiative levels of 1 to 4

In this study, a commercial tara gum-based thickener was dispersed in water and fruit juice at IDDSI levels 1 to 4 and analyzed for steady-flow and oscillatory rheology using a rheometer with concentric cylinder geometry at 5, 25, and 40 °C. The shear stress-shear rate and apparent viscosity-shear rate data were well described by the Herschel-Bulkley and Carreau-Yasuda models, respectively. The zero-shear viscosity and yield stress increased with higher thickener concentration and decreased with higher temperature. The apparent viscosity at 50 s^{− 1} for the thickened samples met the NDD and IDDSI Framework guidelines. Oscillatory rheology showed a gradual transition of thickened diets from liquid-like to solid-like behavior as the thickener concentration increased from DL1 to DL4. Using the time-temperature superposition principle, a single master curve was generated for all diets at 25 °C. The activation energy was determined by plotting the logarithm of the horizontal shift factor (a_T) against temperature using the Arrhenius equation, with values ranging from 27.42 to 118.6 kJ/mol for PT dispersed diets. The study highlights the importance of considering the dispersing medium, storage temperature, and feeding practices for dysphagia patients to prevent structural changes and reduce the risk of aspiration.