43-6 |
Rheology of fluid foods for dysphagic patients |
M. OULD ELEYA, Dept. of Biological Systems Engineering, Univ. of Wisconsin, Madison, Food & Bioprocess Engineering Lab., 460 Henry Mall, Madison, WI 53706 and S. Gunasekaran, Dept. of Biological Systems Engineering, University of Wisconsin-Madison, 460 Henry Mall, 220 Agricultural Engineering Bldg., Madison, 53706. Patients suffering from swallowing disorders (dysphagia) are usually treated through a multidisciplinary approach that includes a diet modification which consists of either altering viscosity of liquid foods by addition of food thickeners or using ready-to-serve pre-thickened fluid foods. The use of viscous fluid foods prevents aspiration by slowing the bolus flow through the oropharynx. In order to ensure a safe management dysphagia, understanding the rheological properties of fluid foods given to dysphagic patients is important. Our objective was to characterize the rheological properties of several fluid foods and two barium sulfate suspensions used for diagnosis of dysphagia. Steady-state flow properties, thixotropy, dynamic response, and creep recovery behavior of six fluid foods and nectar-like and honey-like consistency barium sulfate solutions were investigated using a dynamic rheometer. All samples exhibited a shear-thinning behavior described by the Cross model. The shear stress-shear rate relationships were described by the Herschel-Bulkley model. Barium sulfate suspensions of honey-like consistency exhibited higher viscosity, higher yield stress, and higher elastic modulus than their fluid food counterparts. In contrast, barium sulfate suspensions of nectar-like consistency showed lower viscosity, lower yield stress, and lower elastic modulus than their liquid food counterparts. Frequency spectra of the nectar-like samples were similar to that of a macromolecular solution with both G’ and G” increasing with increased frequency, whereas those of the honey-like samples were gel-like with a little dependency of G’ and G” over frequency. Stress sweep experiments showed that the viscoelastic linear region of fluid foods and barium sulfate suspensions extended up to about 10 Pa. These results suggest that the ready-to-serve fluids on the market exhibit rheological properties significantly different from those of diagnostic barium sulfate suspensions. Therefore, there is a need to develop fluid foods with rheological properties that match exactly those of the diagnostic fluids.
Session 43, Food Engineering: Rheology and texture
|