Principles of microwaving

Microwaves, such as those used in cooking and processing food, are part of the broad spectrum of electromagnetic radiation. Electromagnetic waves are waves of electrical and magnetic energy moving together through space. They include gamma rays, x-rays, ultraviolet radiation, visible light, infrared radiation, microwaves and the less energetic radio waves.

A microwave oven uses microwaves to heat food. Microwaves are radio waves. In the case of microwave ovens, the commonly used radio wave frequency is roughly 2,500 megahertz (2.5 gigahertz). Radio waves in this frequency range have an interesting property: they are absorbed by water, fats and sugars.

When they are absorbed the alternating electromagnetic field generated inside the microwave oven would lead to excitation, rotation/collision of polar molecules and ions inside the food. These molecular frictions would generate heat and subsequently lead to temperature rise.

Microwaves in this frequency range have another interesting property: they are not absorbed by most plastics, glass or ceramics.

The propagation mode of microwave and light is very similar, so microwave has a strong light transfer characteristic. They are all spread in a straight line. And when the microwave encountered an object which has a large size of its wavelength, it will be reflected. And metal reflects microwaves, which is why metals cause spark in a microwave oven.

In microwave cooking, the radio waves penetrate the food and excite water and fat molecules pretty much evenly throughout the food. There is no “heat having to migrate toward the interior by conduction”. There is heat everywhere all at once because the molecules are all excited together.
Principles of microwaving

Popular articles

  • Emulsification process - An emulsion is a mixture of two immiscible liquid phases where one phase is dispersed into another and emulsification is preparation of such a dispersion. ...
  • Macadamia nuts - *Macadamia integrifolia *Maiden & Betche (Proteaceae) is one of the major tree crops of the world. In addition to its nutritional value, macadamia also con...
  • Ebola hemorrhagic fever - Ebola, previously known as Ebola hemorrhagic fever, is a severe, often fatal disease in humans. Similar cases of hemorrhagic fever to Marburg virus were f...