Many of us are familiar with the traditional radiant oven, which usually features a heating element on the bottom, a few cooking racks in the middle, and possibly an upper heating element for broiling. The problem with this radiant heat arrangement is that the heated air remains fairly motionless and food must be placed in the center to avoid the direct heat of the elements. One solution to this dilemma is called a convection oven. A convection oven uses forced air to circulate the heat evenly around the cooking area and avoid the creation of hot or cold spots.
Although the concept of a convection oven was popular in European countries for decades, most American homeowners did not have the option to buy one until Jenn-Air began offering the first models in 1978. Many commercial restaurants rely on a convection oven to give their food more visual appeal, along with improved texture and flavor. The forced air of a convection oven cuts down on overall cooking time, and also allows roasted foods to retain more moisture. It is difficult if not impossible to duplicate the effects of a convection oven when using a standard radiant oven.
One advantage a convection oven has is a more evenly heated cooking space. In a true convection oven, there are three separate heating elements along the top, bottom and rear of the cooking space. When a fan forces the heated air to circulate, it doesn't matter if the food is placed on a top, middle or lower rack. Three separate pans of cookies, for example, can be cooked perfectly in a convection oven, but the heat in a radiant oven cannot penetrate the bottom pan well enough to bake the other two pans evenly. More food can be placed in a convection oven without fear of burning the bottom pan or having half-cooked food on the top rack.
There is also a noticeable improvement in both cooking temperature and time. In the cooking industry, there is a rule dealing with convection ovens called the "rule of 25s". When using a convection oven in place of a radiant one, the cooking temperature can be reduced by 25 degrees with the same end result. This in itself means a substantial savings in heat energy over time. Many foods cook 25% faster in a convection oven, which also means less overall time is needed to prepare dishes.
The nature of convection heating also allows thicker cuts of meat to retain much of their internal moisture. The constant stream of heated air blowing across the surface of the food draws off the excess moisture, which helps to create the external crust many consumers prefer in roasted foods. Breads and pies also benefit from a convection oven because the circulating air quickly browns the outer layers of food but keeps the internal layers moist or light. This is a difficult feat to pull off in a traditional radiant oven, especially when it comes to cooking doughs or batters.
A convection oven is not necessarily the ideal appliance for all of a cook's baking or roasting needs, but it does have some major advantages over standard radiant ovens. Foods can be reheated in a convection oven faster than a conventional oven, without the risk of dehydration or uneven heating often experienced in a microwave. There is a bit of a learning curve when you first learn to cook food in a convection oven, but the professional grade results are often worth the extra financial investment.