Emerging Technologies for Food Processing, 2nd Edition

20.3. Heat and Mass Transfer in Microwave Processing

Microwaves directly interact with food, and heat is generated volumetrically. The mechanisms of microwave heating of foods can be categorized into two types: dipolar rotation and ionic conduction. Some dielectric materials such as water contain permanent dipoles that tend to reorient under the influence of an alternating field, thus causing orientation polarization (Metaxas and Meredith, 1983). Heat is generated as the rotating molecules try to keep pace with the alternating field. In ionic conduction, any charged particles in foods will experience a force alternating at the rate of microwave frequency that will accelerate the particle in one direction and then in its opposite. The accelerated ...