Radiation occurs when energy is transferred by waves from a source to the food.The waves themselves are not actually heat energy but are changed into heat energy when they strike the food being cooked. (Light waves,radio waves, and x-rays are examples of radiation not used for cooking.)

Two kinds of radiation are used in the kitchen:

1. Infrared.

Broiling is the most familiar example of infrared cooking. In a broiler, an electric element or a ceramic element heated by a gas flame becomes so hot that it gives off infrared radiation, which cooks the food. High-intensity infrared ovens are designed to heat food rapidly.

2. Microwave.

In microwave cooking, the radiation generated by the oven penetrates partway into the food, where it agitates the molecules of water.The friction this agitation causes creates heat, which cooks the food.

• Because microwave radiation affects only water molecules, a completely waterless material will not heat in a microwave oven. Plates become hot only when heat is conducted to them by hot foods.

• Because most microwaves penetrate no more than about 2 inches (50 mm) into foods, heat is transferred to the center of large pieces of food by conduction, just as in roasting.

Cooking with microwaves is discussed in more detail later in this chapter.

Continue reading here: Cooking Times

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