The key physical process of cooking is the transfer of heat energy to ingredients to cook them, transforming them and so making them easier to digest and safer to eat. Without the transfer of energy, it is not cooking and the work of transforming raw ingredients to cooked food cannot occur. Of course, there are many other methods of ingredient or food preparation, and they generally involve other processes, either simply cleaning (and perhaps freezing) for raw foods or some preservation technique such as dehydration, pickling or smoking. However, cooking involves heat or energy transfer.
- Cooking can be defined in a general way as the transfer of energy from a heat source to the food. Our various cooking methods - boiling, broiling [grilling], baking, frying and so on - achieve their various effects by employing very different materials - water, air, oil - and by drawing on different principles of heat transfer."
Physical Aspects Of Heat Transfer
There are three ways in which energy can be transferred:
- Conduction: Direct Contact: important for determining the type of cooking utensil;
- Convection: Movement in Fluids: heat transfer through a medium like air, oil or water, as in boiling, steaming and frying;
- Radiation: Energy from Radiant Heat and Microwaves: represented by broiling (grilling), spit-roasting, barbecuing and microwaving.
While they are treated separately above, generally combinations of the different forms of heat transmission are used during most types of cooking, e.g. cooking spaghetti in a pan of boiling water over a gas flame includes radiant heat and convection of heat via the air from the flame, conduction through the materials in the pan itself and then convection through the heated water in the pan.
Methods of Heating Foods
These methods of energy transfer can be further subdivided into several different ways:
- Baking: Convection and Radiation
- Boiling and Simmering: Convection
- Deep Frying: Convection
- Grilling and Broiling: Radiation
- Microwave: Radiation
- Pan Frying and Sautéing: Conduction
- Steaming: Vapour Condensation and Convection
These methods transform and brown food via three main methods:
- Davidson, A. (1999) The Oxford Companion to Food, Oxford University Press. ISBN 0192115790.