Development of an objective method for assessing viscosity of formulated foods and beverages for the dysphagic diet.

Objective: To develop and validate a practical, economical, and objective viscosity assessment tool, the line-spread test, for foods and beverages formulated for the dysphagic diet. The line-spread test is based on the measure of product dispersion over a flat surface.
Design: Viscosity-altering formulations for a selection of soups and beverages commonly served to patients with dysphagia at a local hospital were developed under controlled conditions. The samples were presented to a trained sensory panel for evaluation by quantitative descriptive analysis and were measured by the line-spread test. Numeric results of the two tests were compared.
Setting: The Food Research Laboratory with private sensory booths at Mount Saint Vincent University.
Main Outcome Measures: Results of the sensory evaluation and the line-spread test would strongly correlate, indicating predictive validity, but the line-spread test would be more reliable and show variability in measurement.
Statistical Analyses Performed: Correlation, analysis of variance (ANOVA), and standard deviations (calculated from the within-group mean square error of the ANOVAs).
Results: ANOVA showed that both the sensory panel results and the line-spread test values indicated significant differences among the samples. Standard deviations indicated less variability in line-spread values. There was a strong positive correlation (r = .90 to .97) between the two types of results, which indicated strong predictive validity for the line-spread test.
Applications: The line-spread test is a reliable and valid tool to assess viscosity of formulated foods and beverages for the dysphagic diet and can be readily and economically adapted to any dietary department for product development and quality control.