Assessment of Functional Food Dioscorea Japonica Paste As A Thickened Liquid For Elderly With Dysphagia

Background: In the elderly, reduced mastication and swallowing functions result in malnutrition and deterioration in the quality of life. As individuals age in the society, the novel concept of dysphagia diet is essential in order to prevent lifestyle and chronic diseases and maintain nutrition intake. Recently, we reported that Dioscorea japonica, a wild yam, has preventive effects on chronic inflammation via the inhibition of proinflammatory lipid mediator synthesis. The paste of Dioscorea japonica showed conformable physical properties as a thickened liquid for patients with dysphagia in rheological analysis. In the present study, we focused on the unique physical properties of Dioscorea japonica paste and evaluated its stability and usefulness as a thickened liquid compared with commercially available thickened liquids. Methods: The paste prepared using a uniformly freeze-dried Dioscorea japonica powder could suitably modify the viscosity by altering the blending amount. Viscosities of the Dioscorea japonica paste, xanthan gum, and commercially available thickened liquids were measured using a cone and plate viscometer after 1 min by employing the following setting: temperature of 20°C and shear rate of 50 s−1. The effect of changes in temperature and pH, and addition of NaCl and α-amylase, on viscosity was compared among the thickened liquids. Results: Compared with the other commercially available agents, the Dioscorea japonica paste was stable in terms of viscosity on the addition of NaCl, and no change was observed on the addition of α-amylase as similar as the others. Although the Dioscorea japonica paste was relatively stable in terms of viscosity with change in pH, it was slightly unstable with change in temperature. Conclusion: The findings of this study indicate that the Dioscorea japonica paste is useful as a novel type of thickened liquid for patients with dysphagia.