The objectives of our study were 1) comparing the rheological characteristics of two commercial gum-based thickeners with different composition, dissolved in water under standard conditions, and 2) perform a sensory analysis (with both adults and institutionalized elderly) to detect different viscosities within the same texture (nectar and honey). Our hypothesis was that viscosity ranges established by the scientific societies, such as the National Dysphagia Diet Task Force (NDD), seem to be very wide and individuals might be able to detect small differences within the same texture range. Moreover, we have not found sensory studies of viscosity in institutionalized elderly. Knowledge of the rheological and sensory characteristics of the various thickeners in elderly is limited, although it has been seen that there are differences between the rheological behaviors of gum-based thickeners with different composition. Further studies of this and other tools are necessary to identify inexpensive practical tools for quantification of thickened liquid consistency.The prevalence of dysphagia is very high in institutionalized elderly. Thus, the results of the current study suggest that the LST may be useful in the broad categorization of fluids into therapeutically significant groupings but that it cannot be used more specifically to measure fluid viscosity. Furthermore, the LST was not predictive of viscosity. Whereas the LST was able to separate the juices into nectar and honey categories, it was not able to separate barium mixtures into these categories nor compare barium to juices. Twenty-six liquids (10 powder-thickened 'nectar' juices, 10 powder-thickened 'honey' juices, and 6 barium mixtures) were assessed using both a viscometer for objective measurement of viscosity and the LST. The current study analyzed the utility of the Line Spread Test (LST) in this regard. This lack of standardization leads to variability in practice and points to the need for a simple tool for clinicians to assess thickened liquid consistency. Although dietary modification is a common treatment strategy used to manage dysphagic patients who aspirate thin liquids, there are no standard definitions for thickened liquid preparation.

The line spread test for viscosity