An alternative elongational method to study the effect of saliva on thickened fluids for dysphagia nutritional support

Powder thickeners are used to modify liquid consistency in dysphagia management. These thickeners may contain starches, gums or their mixtures. Since the salivary α-amylase enzyme favours starch hydrolysis, this might affect the overall rheology of thickened fluids. This study provides a first insight into the impact of salivary α-amylase on the elongational properties of different types of thickened fluids, differentiating between gum-based and starch-based fluids, when considering the axial force developed during uniaxial elongation. The experimental results obtained in this study showed a dramatic decrease in the axial force as a result of salivary α-amylase addition to a pudding-like starch-based thickened fluid, while no significant change was observed after addition to a pudding-like gum-based thickened fluid. Monitoring axial forces during the stretching phase of CaBER was found to be a quick alternative method to identify structural changes of pudding-like thickened fluids in the presence of saliva, for which the conventional CaBER experiments are technically limited.