The terms roasting and baking are today to a great extent interchangeable and are used to describe the operation of cooking in an enclosed and heated space. The heat is conveyed to the food partly by conduction through the metal runners and sheets on which the food is placed, but mainly either through direct radiation from the walls of the oven or by convection currents in the heated air. In some ovens described below the heat is conveyed almost entirely by convection currents, the oven being designed with an electric fan which develops forced air convection. This increases the rate of flow of the heated air and consequently the rate of transfer of heat to the food. Usually the term roasting is applied to the cooking of meat and vegetables while standing in hot fat in an oven.
Originally roasting was carried out on a spit in front of a fire, no oven being used, but today for reasons of efficiency and cleanliness the oven has taken the place of the spit. The advantages of the method of cooking on a spit have however been re-valued recently and electrically driven rotisseries have come into use particularly for poultry, game and small joints. The operation of baking covers the use of the oven in the making of bread, cakes: pastry and made up dishes, and for this purpose no other piece of equipment is possible. In both baking and roasting a fundamental factor is the production of food with an attractive external appearance. the result of cooking in the dry radiant heat of an enclosed space.
The process of grilling is closely allied to roasting and baking but in this case an oven is unnecessary. The source of radiant heat may be either incandescent fuel, as on an open fire grill, or red hot metal, as in a gas or electric grill. The heat may be applied from above or below, and historically the term grilling is applied to the latter only–the open fire grill. A grill which applies top heat is often referred to as a Salamander, a term which originates from the early practice of obtaining a brown surface on food during cooking by the application of red hot iron. The Salamander was a circular iron plate carried at the end of a long rod; this was heated until red and then passed slowly over the surface of the food.
In the process of frying heat transfer by radiation is not used at all. Instead, the food is cooked by the conduction of heat through a bath of hot fat in which it is totally or partially immersed. By this method there is a very rapid transfer of heat to the food and although the temperature of the fat is much lower than that of the elements used in grilling, the temperature at the surface of the food may be quite as high in frying as in grilling.