Comparison of Simple Evaluation Methods for Thickened Liquids with Different Thickening Agents
The Japanese Journal of Dysphagia Rehabilitation
Objective: The Japanese Dysphagia Diet 2013 (JDD2013) for thickened liquids was designed as a three-level categorization system of thickness, which explained not only the drinking and visual properties, but also the viscosity ranges at a shear rate of 50 s −1 , and the ranges of line spread test (LST) values. However, LST is inadequate for thickened liquids containing different types of thickening agents and nutritional liquids containing proteins or fats. Recently, simple evaluation methods
... thickened liquids using funnels or syringes have been reported. In this study, we investigated the most suitable method for evaluating thickened liquids. Methods: The samples were commercially available orange juices thickened by thickening agents containing xanthan gum (X), guar gum (G) or starch (S). The viscosities of the samples were controlled around 50, 150, 300, and 500 mPa・s at a shear rate of 50 s −1 . LST was performed in accordance with JDD2013, and the flow limits of the liquids were read. The funnel method measured the time at which pouring of thickened liquid (30 mL) into a funnel started till the end of outflow from the funnel by a stopwatch. On the other hand, in syringe method the nozzle of the syringe was covered with a finger, followed by filling of the syringe with thickened liquid up to the 10-mL mark. The finger was then removed from the nozzle and the scale of the remaining liquid volume left after 10 s was recorded. We then measured the viscosities of samples at shear rates of 1, 5, 10, 50, 100, 500, and 1,000 s −1 and performed sensory evaluation in the mouth cavity to verify the aptness of these methods. Results: The samples prepared with the same thickening agent showed smaller flow limits of LST for more viscous liquids. However, the flow limit of the sample G was longer than those of the samples X and S, whose viscosities were lower. For the funnel method, when the viscosity of the sample was high, the outflow time was long irrespective of the type of thickening agents. In syringe method, the higher the viscosity of the sample, more was the remaining volume. However, the remaining volume in high-viscosity sample G was less than that of the low-viscosity sample X. Conclusions: The funnel method was found to be suitable for simple evaluation of thickened liquids in this study.