ABSTRACT
Microwaves are part of the electromagnetic spectrum and are composed of electric and magnetic fields. In microwave heating of food, the electric fields of the microwaves interact primarily with water molecules and ions in the food material, generating heat volumetrically. Microwave heating can potentially supplement and/or replace conventional surface heating in almost any food process. Thus, the application of microwave heating can be in just about any food process involving heating-reheating, thawing, drying, pasteurization, and so on. The heat generated by the microwaves is nonuniform and therefore creates temperature gradients, which, in turn, causes diffusion, flow, and change in properties that alters the volumetric heat generation itself. This makes microwave heating and its modeling quite interdisciplinary. As shown in Figure 1, it involves electromagnetics, heat transfer, moisture transfer, and kinetics of biochemical changes. Although microwave heating involves coupling of so many different physics, to simplify things the sections in this chapter are organized in terms of a somewhat
artificial division of subject matter along the lines of various engineering disciplines. Thus, they are presented in the following order: rigorous electromagnetic modeling without and with heat transfer, simplified electromagnetic modeling with application to heat transfer in solids, heat and moisture transfer in solids, and heat transfer in fluids.
