Cooking Food • Food is cooked to • Prevent food poisoning by killing micro organisms. • To make it more tasty and easy to eat • To preserve it • To make it easier to digest • So it is easier to absorb the nutrients • To reduce the bulk.
Heat transference • Heat transference changes food physically and chemically. • Heat can be transferred using wet or dry methods. • When you heat /cook food you often use more than one method.
Conduction • In conduction the molecules are heated and begin to vibrate faster and so the bump into the next molecule and pass on the energy. This usually takes place in a pan or inside the food.
Convection • Convection takes place in the air or in a liquid. • As the molecules become hotter they rise and then fall when they become cold again. • In a pan of boiling water you can see the hot liquid rising and the bubbles bursting on the top. • Convection takes place in the air of the oven, in water and in hot fat.
Radiation • Radiation is the transfer of energy from a heat source such as a grill to the food. • The radiation waves usually travel in a straight line. The centre of the food is then cooked by conduction.
Microwave • This is a different type of radiation wave as it travels deeper into the food. Electricity is converted into microwaves by the magnetron. • The microwaves travel 5cm into the food . • They then make the water molecules vibrate which causes friction which then makes the heat. • Hot spots can be found inside of the food so it is important to stir the food or leave it to cool before eating.