Microwaves cook and reheat food quickly. They are also used in a wide variety of other ways. They help detect speeding cars, send telephone and television communications, cure rubber and wood products, raise bread and doughnuts, and even disinfect kitchen sponges.
The microwave oven works through a process called dipole rotation. Basically, the electromagnetic radiation from the oven passes through water molecules in food and creates an electric field that changes the polarity of these molecules millions of times per second. This causes the molecules to rotate, creating friction that heats up the food.
Inside the microwave oven, a transformer steps up the electricity from 120V (in the US) or 110V (in Europe) to around 4000 volts. This voltage is needed to power a filament at the heart of the device, which then heats up and generates microwaves. A circular magnet is positioned near the filament, and it pulls electrons from the heated filament to loop back around itself, which creates the microwave electromagnetic radiation that cooks your dinner.
In addition to increasing protein heat denaturation and aggregation, excessive microwave heating can cause the loss of functional groups in proteins that are important for their antioxidant, foaming, gelation, oil absorption and other properties. These functional groups can affect the final product’s appearance, texture and flavor.
Microwave energy is reflected by metals, passes through glass and paper, and is absorbed by foods. The rotation of the water molecules in food, along with friction between these molecules, generates heat that cooks and reheats the food.