Linear and non-linear viscoelasticity of puddings for nutritional management of dysphagia

Abstract: Dysphagia, or abnormal swallowing of foods and/or liquids, may result as a consequence of different common diseases. Management of dysphagia is commonly done by the prescription of texture-controlled diets. The aim of the present study was to characterize the rheological behaviour, as a function of ageing, of a new ready-to-serve dysphagia diet food with spoon-like consistency (pudding). Linear (small amplitude oscillatory shear) and non-linear (steady-state flow and relaxation) material functions were measured as a function of product shelf-life at different storage temperatures. From the experimental results obtained, it may be concluded that both linear viscoelasticity moduli and viscosities of the commercial pudding studied always increase with ageing, showing maximum values for samples stored at 40 °C. A power-law model describes the frequency dependence of pudding elastic modulus. The power-law index shows minimum values for the sample stored at 40 °C, and does not depend on ageing. Linear viscoelasticity functions versus frequency curves, as a function of ageing, can be superposed into a master one. The non-linear relaxation modulus is factorable into time and strain dependent components. Commercial pudding Sauter’s diameter increases with ageing and storage temperature. However, the differences are not large enough to explain the significant increase in the rheological functions found during storage at high temperature. Protein aggregation enhancement in the continuous phase, during storage at high temperature, may explain the experimental results obtained. [Copyright &y& Elsevier]