Comparison of the Rheological Properties of Ready-to-Serve and Powdered Instant Food–Thickened Beverages at Different Temperatures for Dysphagic Patients

BackgroundDysphagia, or difficulty swallowing, affects an estimated 15 million Americans. Its management may include use of instant food thickener (IFT) to modify beverage consistency to minimize the risk of aspiration and prevent dehydration. However, inconsistencies with the desired viscosity of these thickened liquids occur both within and across product lines for both ready-to-serve commercially packaged prethickened (CPPT) and IFT-thickened beverages.ObjectivesTo examine the rheological property differences between CPPT and similar IFT-thickened beverages, and to assess the stability of these products at two temperature ranges using three viscosity measurement techniques.DesignThe rheological properties of five CPPT and IFT-thickened beverages at both nectar- and honey-like consistencies were evaluated at 10°C (50°F) and 20°C (68°F) using the line spread, funnel, and viscometry methods.Statistical analysisOne-way analysis of variance was used for data analysis. When a significant difference was observed, Tukey’s test was used to separate the means.ResultsEach viscosity measurement technique showed the CPPT nectar- and honey-like consistency beverages were significantly more viscous (P<0.0001) at both temperatures compared with their IFT counterparts. Moreover, CPPT beverages at nectar and honey consistencies were almost always more viscous than the National Dysphagia Diet Task Force–defined standards, whereas the IFT-thickened beverages were more frequently within those standards.ConclusionsA reevaluation of the viscosity of CPPT beverages with reference to the National Dysphagia Diet Task Force set standard ranges needs to be considered. A strong need also exists for development of a standard protocol on product labels that includes the expected rheological properties of CPPT and IFT-thickened beverages. To the clinicians, especially registered dietitians, it is an important clinical consideration to recognize that CPPT products may be thicker than IFT-thickened products and also may be more viscous than the National Dysphagia Diet Task Force–defined standards.