Convection ovens heat food from the bottom and the top, but they also have one thing that conventional ovens do not have that makes a huge difference; convection ovens have a fan which circulates the hot air right onto the food.
Convection ovens work differently than their conventional counterparts, where food is heated from the bottom. Convection ovens utilize a fan to circulate hot air throughout the enclosure and around food. Dishes prepared in convection ovens cook faster than in a regular oven because the moving air can surround and penetrate more thoroughly.
Convection ovens have the ability to cook evenly, so bakers can cook more food at the same time. For example, someone with a conventional oven has three racks for holding food. The top rack is close to the heating element at the top of the oven. Similarly, the bottom rack is near the heating element at the bottom of the oven. A third rack in the middle is not near either one and will take longer to cook. If a baker were to arrange French fries in this manner, the fries on top and bottom would be finished cooking before the ones in the middle were even warm.
Another advantage is that the convection ovens circulating heat enables even cooking no matter how much food is in the oven. Dishes can be stacked on oven shelves from top to bottom, so long as an inch or two of space is allowed between pans. The fan ensures that heat will penetrate all levels, where a regular oven will finish the bottom dishes quicker than those on top. Because the built-in fan circulates air, the heat is more evenly distributed. This results are fewer "hot spots" and less turning of baking sheets to ensure uniformity. Even heat also prevents burning and shrinkage of food due to unbalanced loss of moisture.
Because the food is being blown with hot air from the oven's fan, it will not just cook more evenly, it will also cook faster than in a conventional oven. As the food receives heat from the fan, it creates a chemical reaction within the food which speeds up the cooking process.
The same method of cooking that makes a convection oven attractive to some can be a nuisance to others. Because the built-in fan must rotate to circulate the air, it will also blow any lighter objects in the oven. If parchment paper or foil are not properly secured or weighed down, they can loosen from a pan and waft throughout the oven. Not only can this irritate the chef and prevent proper cooking, but it can also be a fire hazard.
Also, for those unfamiliar with cooking in a convection oven, the method can be a tough adjustment. Typically, a convection oven guide will advise a 25 percent lower temperature and shorter cooking time as compared to regular oven recommendations. For cooks used to a regular oven approach, some experimentation may become necessary before becoming accustomed to convection ovens.
There is nothing as satisfying as being able to produce restaurant quality meals from a home kitchen. A convection oven can change the experience that a family is having with food and turn them into foodies.