Microwave heating of low-loss dielectric food products
Résumé
In this study, a microwave heat treatment is applied to a whey proteins isolate (WPI) powder in a dry state. The thermophysical properties of the WPI powder (density, specific heat and thermal conductivity) were measured or taken from literature. A dielectric characterization using a resonant cavity perturbation technique is also presented and the measurements confirmed the low dielectric loss factor of the sample.
A 3D numerical model, which includes a single mode microwave cavity working at 2.45 GHz, is also developed to understand the microwave interactions with the powdered food. Simulation results are discussed on the one hand in terms of electromagnetic field propagation within the rectangular waveguide and on the other hand by considering the temperature distribution within the powdered food. The model is experimentally validated with a pilot-scaled microwave equipment (2.45 GHz solid-state microwave emitter, impedance tuner and optical fibers probes). This study will give significant guidelines for the microwave heating optimization of low-loss dielectric products such as powdered food materials.