Kitchen Physics

• Cooking an egg is a relatively simple thing at its heart. You apply heat to your egg, and you stop once it's cooked to your liking. The underlying science isn't all that important. You don't usually need to know the details of how proteins coagulate under the influence of heat or understand the mechanics of heat transfer to make breakfast. That said, a good understanding of heat transfer can help you choose the correct cooking method for any given food.

Conductive Heating

• Conductive heating is one of the simplest ways to cook anything. In the process, heat goes directly from a heat source -- anything from an open fire to a modern gas stove -- to the pan. The pan, in turn, absorbs heat and conducts it to the food. This is what griddles and skillets do, either on the stove top or as freestanding countertop appliances. In short, once you get past the unfamiliar terminology, conductive heat is how you prepared every egg you've ever fried.

The Ins and Outs of Conductive Heat

• One of the biggest advantages of conductive heat is that it's very fast, especially for small pieces of food such as an egg or a thin chop. With something as delicate as an egg, however, it can sometimes be a disadvantage as well. Proteins tend to contract and toughen if they're cooked at too high a temperature, and overheated eggs can easily become rubbery or develop a scorched flavor. Lightweight skillets can sometimes give unsatisfactory results as well, because they quickly warp in regular use and can cause the eggs to cook unevenly.

Convection Heating

• Aside from conductive heating through a skillet or griddle, almost all other common egg preparation methods use forms of convection heating. In convection heating, the heat energy is conveyed by currents of air or liquid, rather than by direct contact with the pan. This might include baking a quiche or a dish of shirred eggs, where the heat is conducted by air currents within the oven, or boiled and poached eggs where water provides the convection heat. Even deep frying -- used for sausage-coated Scotch eggs -- uses convection heat, conveyed by the cooking oil.