Effects of Liquid Base, Time, and Temperature on Viscosity

Date of Graduation

Spring 2004


Master of Science in Communication Sciences and Disorders


Communication Sciences and Disorders

Committee Chair

Lynette Goldberg


The purpose of this study was to examine the effects of liquid base, time, and temperature on viscosity using two commercially available thickening agents. Liquid bases used were 2% milk, pulpless juice and coffee. Prescribed amounts of thickener were used to achieve a honey-thick consistency following National Dysphagia Diet guidelines. Viscosity levels were measured at three temperatures: room temperature, refrigerated, and heated. Viscosity measurements were performed at the following time intervals: initial, 15-min., 30-min., 60-min., and 120-min. A total of 900 samples were analyzed using a Brookfield Dial Viscometer. Statistical analyses showed that coffee and milk samples were more viscous than orange juice samples, heated samples were more viscous than refrigerated or room temperature samples, and that the viscosity of thickened liquids changed over time. There was a significant difference in the initial and 15-min. time intervals when compared to the 30-min., 60-min. and 120-min. time intervals. Results imply that it is optimal to use thickened liquids within 15-min. of preparation in order to ensure that the desired consistency is maintained. Furthermore, adults with dysphagia who require hydration through thickened liquids may prefer orange juice over coffee and milk, and liquids that begin at refrigerated or room temperature, rather than liquids that are heated and thickened. The type of liquid base used, and the temperature and time at which liquids are prepared and served are important variables to consider for patients who require nourishment using thickened liquids.


dysphagia, viscosity, liquid base, time, temperature

Subject Categories

Communication Sciences and Disorders


© Karen Sandridge