Rheological Properties and Stability of Thickeners for Clinical Use

The adaptation of liquids for patients with dysphagia requires precision and individualization in the viscosities used. We describe the variations of viscosity in water at different concentrations and evolution over time of the three compositions of commercial thickeners that are on the market (starch, starch with gums, and gum). By increasing the concentration in water, the viscosity of gum-based thickeners increases linearly, but it did not reach pudding texture, whereas the viscosity of the starch-based thickeners (alone or mixed with gums) rapidly reaches very thick textures. We modeled the viscosity at different concentrations of the four thickeners using regression analysis (R-2 > 0.9). We analyzed viscosity changes after 6 h of preparation. The viscosity of gum-based thickeners increased by a maximum of 6.5% after 6 h of preparation, while starch-based thickeners increased by up to 43%. These findings are important for correct handling and prescription. Gum-based thickeners have a predictable linear behavior with the formula we present, reaching nectar and honey-like textures with less quantity of thickener, and are stable over time. In contrast, starch thickeners have an exponential behavior which is difficult to handle, they reach pudding-like viscosity, and are not stable over time.

Automated summary

The adaptation of liquid diets for dysphagia patients requires precise and individual adjustments based on viscosity. This study investigated viscosity variations of different concentrations of water and the time evolution of three types of commercial thickeners (starch, starch with gums, gum-based). The findings showed that the viscosity of gum-based thickeners increases linearly with increasing water concentration but does not reach pudding-like texture. On the other hand, starch-based thickeners (alone or combined with gums) rapidly reach very thick textures. The study also modeled the viscosity of the four thickeners at different concentrations and analyzed viscosity changes after 6 hours of preparation. Gum-based thickeners had predictable linear behavior, reaching nectar and honey-like textures with less thickener, and remained stable over time. In contrast, starch-based thickeners exhibited exponential behavior, reaching pudding-like viscosity and being unstable over time.