Rheological modification of fluid foods for patients with dysphagia

Swallowing disorders, or dysphagia, is a growing problem especially as the population gets older. Fluid thickening is a well-established strategy for treating dysphagia, but the effects of thickening on the physiology of impaired swallowing are not fully understood and the relations to basic rheology are scarce. Commercial thickeners studied showed different behavior in both shear thinning, yield stress and first normal stress difference, and even larger differences in extensional viscosity. INTRODUCTION Swallowing disorders, or dysphagia, is a growing problem especially as the population gets older. Already over 50 years of age 22% suffer from swallowing disorders and in the age group above 70, 40 % suffer due to factors such as degenerative diseases and side effects of medication. It is estimated that 99 million people, i.e. 8% of the world population suffers from dysphagia. These persons must eat texture adjusted foods. Healthy individuals apply highly unconscious, but very well coordinated strategies for the oral processing producing easy-to-swallow boluses. People who suffer from dysphagia have impaired swallowing mechanisms. One serious case is when the epiglottis does not fully function and food or beverage leaks into the larynx (aspiration), which is common in the elderly population. Dysphagia is a prevalent symptom in degenerative diseases such as stroke, dementia, Parkinson’s disease and Alzheimers’s disease. Swallowing disorders covers a broad range of problems, from coughing during meals to malnutrition, and 30-60% of the patients in homes for the elderly are estimated to be malnourished. Foods that give a better controlled passage through the opening to the larynx, even with a malfunctional epiglottis, will make a significant contribution to an improved quality of life for people with dysphagia. Fluid thickening is a well-established management strategy for dysphagia. Fluid foods are thickened with hydrocolloids which provide increases shear and extensional viscosity. However, the effects of thickening on the physiology of impaired swallowing are not fully understood and the relations to basic rheology are scarce. Fluids are commonly thickened using commercial thickeners consisting of mixtures of hydrocolloids such as starches, guar and xanthan, to a perceived consistency or to a measure of shear viscosity at a specific shear rate, typically 50 s. The guidelines vary according to country, but the American Dietetic Association guidelines 5 are often referred to. They give a perceived consistency and apparent viscosity at an apparent shear viscosity at 50 s as Rheological modification of fluid foods for patients with dysphagia Waqas Muhammad Qazi1 and Mats Stading1,2 1 SP Technical Research Institute of Sweden, Soft Materials Science, Gothenburg, Sweden 2 Chalmers University of Technology, Göteborg, Sweden Simultaneous In-situ Analysis of Instabilities and First Normal Stress Difference during Polymer Melt Extrusion Flows Roland Kádár, Ingo F. C. Naue and Manfred Wilhelm 1 Chalmers University of Technology, 41258 Gothenburg, Sweden 2 Karlsruhe Institute of Technology KIT, 76128 Karlsruhe, Germany ANNUAL TRANSACTIONS OF THE NORDIC RHEOLOGY SOCIETY, VOL. 24, 2016