Summary of the Experiment:
The study explored the use of Ultrasonic Spinning Rheometry (USR) to evaluate the rheological properties of dysphasia diets, which are typically heterogeneous foods lacking effective evaluation tools. The experiment aimed to obtain effective viscosity curves of these foods using USR and to assess the time variations of viscosity due to enzymatic reactions. The foods tested included a total nutritional drink, tomato juice, and rice gruel, each representing different levels of complexity and viscosity as classified by the Dysphasia diet pyramid.
UVP-DUO Usage:
The UVP-DUO by Met-Flow was utilized to measure the velocity profiles necessary for USR. The experimental setup involved a cylindrical vessel oscillated sinusoidally to create azimuthal flows, with UVP-DUO capturing the radial profile of azimuthal velocity components. Key setup parameters included:
- Ultrasonic Frequency: 2 MHz
- Transducer Diameter: 24 mm
- Number of Cycles: 4
- Channel Width: 1.48 mm
- Number of Repetitions: 128
- Sound Velocity: 1480 m/s
- Output Voltage: 90 V
- Number of Samples: 1024
Result of the Experiment and How UVP-DUO Contributed:
The experiment yielded detailed viscosity curves for each test fluid. For the total nutritional drink, strong shear-thinning behavior was observed with viscosity data fitting a power law model. For tomato juice, a wider range of shear rates was captured, also exhibiting shear-thinning properties. The most complex test, involving rice gruel with added α-amylase, demonstrated the ability of USR to track the enzymatic hydrolysis process, showing viscosity reduction over time and transitioning towards Newtonian fluid behavior.
How UVP-DUO Helps to Evaluate Rheological Properties of Heterogeneous Foods