Background – Dysphagia (swallowing disorders) affects 30-60% of nursing home residents giving rise to serious health issues, amongst which is dehydration is the most important affecting up to 25% of non-ambulatory residents. Thickened fluids are used to manage dysphagia but their efficacy is modified by the particular thickening agent, the liquid medium being thickened and lack of standardised preparation to achieve a given density and viscosity. Objective – To determine the rheological properties of fluids (fruit juices, cordials and milk) thickened with commercially available thickening agents.
Design – Laboratory based measurement of density and viscosity of thickened fluids at 20°C using a strain controlled rheometer. Yield stress was extrapolated from rheology data.
Outcomes – The density, yield stress and viscosity of the thickened fluids were significantly influenced (P < 0.05) by the type of dispersing liquid and thickener (xanthan or guar gums and modified starch). Rheological models,
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determined for each medium, were used to predict the viscosity at an assumed shear rate of 50s
Physical properties of thickened food are sensitive to changes in solids content, and errors in preparations can be better minimised using weights rather than volumes from scoops and spoons that are not standardised.
Conclusions – The rheological models defined in this study can be used as the basis of a standardised method of preparation of thickened fluids. Reduced compliance with fluid intake due to incorrect fluid preparation affects hydration state. Elderly persons may then suffer poor nutrition, dwindling health and medical complications associated with failure to thrive.