Cooking is defined as energy being transferred from a heat source to a food item or items. What are the methods of heat transfer in cooking?
The methods of heat transfer in cooking are; conduction, convection, radiation or a combination of these. The energy we are using here is heat and through these heat transfer methods we derive the method of cooking where food item can be prepared by using cooking methods such as saute, bake, broil, etc.
When heat is applied to a food item, the heat, as energy, makes the molecules of the item vibrate and expand. Through this movement they bounce off of each other distributing the energy in this case heat. Here are brief explanations of cooking and heat transfer for food items.
Conduction of heat is accomplished through an item transferring heat to another item by contact. Grilling a steak is a food item that can be prepare by using the method of conduction where the heating source, the flame, touches the food directly. The fact that conduction must have contact between the heat source and the food item makes conduction a slower method to cook. The example above where molecules collide to transfer energy is conduction in action. As the molecules of the food item near the heat source heat up they move more rapidly creating friction which transfers heat energy from the outer area to the interior. This is how a steak can be cooked thoroughly on the outside but still be rare on the interior.
Metals conduct heat very well so your cookware is all made of metals; aluminum and copper being the best conductors of all. Gases and liquids are poor conductors so steaming an item will take longer than grilling or pan sauteing.
Convection is heat transfer through the use of a fluid as the conducting material. The fluid can be either liquid or gas and is circulated either by natural or mechanical methods.
The natural method uses the principle of heated gas will rise while cooler gas will fall combined to create circulation.
Mechanical methods are used in modern ovens and happens through the use of fans. Ovens using convection will cook items evenly and in less time than with a conventional oven.
Radiation is where heat is transferred through waves that can be heat, light or radio. Microwave ovens through the use of microwave technology use radio waves to heat certain molecules while not heating others. This allows the food item to cook while the container remains cool. Infrared is another technology being used to cook items through either heat or light.
Through these three methods of heat transfer in cooking. These methods are used to transfer heat to a food item while the distribution of the heat within the food item will always be through conduction. It is through the understanding of types of heat transfer in cooking methods that we can better understand the subtle ways we can use this heat to produce different and unique meals.