Posted: Jul 25, 2006
While more expensive than traditional ovens, convection ovens provide numerous advantages over non-convection ovens. They can cook food in as little as half the time of static air, and do so at lower temperatures. As a result, foods shrink less, increasing yield and lowering effective food cost. Meats such as prime rib finish crispy on the outside, but remain tender and juicy on the inside with convection oven cooking. The crusty exterior provides a seal retaining moisture and flavor. Convection ovens speed up chemical reactions that occur when food is cooking as well. The sugars in vegetables caramelize faster, baked goods release steam more quickly, and roasted meats render fats in half the time as with conventional roasting.
‘Convection’ is defined as heat transfer in gas or liquid form by the circulation of currents from one region to another. Water boiling in a pot and hot air moving in an oven are both examples of using convection to heat food. In a convection oven, electric elements or gas burners heat the air while a high-speed fan blows it around the oven cavity, thereby speeding up the cooking process.
When food is heated in a conventional oven, the heat exchange between the hot air and the cold food and the evaporation of moisture in the food create an actual layer of insulation on the food’s surface. As this insulation barrier forms, the cooking process slows down. The forced air currents in a convection oven blow away this insulation layer and replace it with hot air, so the heat transfer is far more efficient.
Air currents serve to amplify the effects of temperature. For example, the same principal that causes the wind chill factor on a blustery winter day works to increase the effectiveness of heat in an oven. When baking, the convection oven temperature may be reduced by 25° F, keeping the cooking time and temperature approximately the same as conventional baking, and one will achieve optimal cooking results. You save energy, decrease shrink and put more profit on the bottom line.
In a static air oven, food must be placed near the center because the bottom rack is more susceptible to overcooking or burning. Likewise, food placed near the top of the oven often overcooks because rising heat can accumulate there. Convection ovens have both upper and lower heat sources to prevent hot spots as well as a third heat source placed in the back of the oven near the fan to ensure that the fan will be blowing hot air. The oven’s internal temperature remains constant top to bottom, and side to side because the air in the cavity is constantly circulating. Since the heat-circulating fan is not inside the oven cavity, the oven can be almost completely filled as long as an inch of space is left for the air to circulate between the food and the oven walls. This delivers a greater yield as well as saving energy.
As versatile and efficient as convection ovens are, they are not for everything. Meat, poultry, fish, and seafood all cook extremely well by convection. However, convection cooking only works when the moving air comes in direct contact with the food; meats cooked in a closed roaster, casseroles, cobblers, etc. will not cook much differently in a convection oven than they do in a standard model. Dark and dull pans will tend to cause over-browning when used in convection oven cooking. Anything covered or partially sealed is best baked in a conventional oven.
Overall, convection ovens are a great investment to make in order to increase productivity and effectiveness in the kitchen. With many gas or electric models and sizes avaialble, you should be able to find one to fit your needs, whether it's for commercial or home use.
Watch a video (5:09) on Imperial convection ovens here.