A convection oven (also known as a fan-assisted oven, turbo broiler or simply a fan oven or turbo) is an oven that has fans to circulate air around food to create an evenly heated environment. The increased air circulation causes a fan-assisted oven to cook food faster than a conventional non-fan oven, which relies only on natural convection to circulate the hot air. [1] Fan-assisted convection ovens are commonly used for baking as well as non-food, industrial applications. Small countertop convection ovens for household use are often marketed as air fryers.
When cooking using a fan-assisted oven, the temperature is usually set lower than for a non-fan oven, often by 20 °C (36 °F), to avoid overcooking the outside of the food.
Convection ovens distribute heat evenly around the food, removing the blanket of cooler air that surrounds food when it is first placed in an oven and allowing food to cook more evenly in less time and at a lower temperature than in a conventional oven. [2]
The first oven with a fan to circulate air was invented in 1914 but it was never launched commercially. [3]
The first convection oven in wide use was the Maxson Whirlwind Oven, introduced in 1945. [4]
A convection oven has a fan with a heating element around it. A small fan circulates the air in the cooking chamber. [5] [6]
One effect of the fan is to reduce the thickness of the stationary thermal boundary layer of cooler air that naturally forms around the food. The boundary layer acts as an insulator and slows the rate at which heat is transferred to the food. By moving the cool air (convecting it) away from the food the layer is thinned, and cooking is faster. To prevent overcooking before the middle is cooked, the temperature is usually reduced by about 20 °C (36 °F) below the setting used for a non-fan oven. In a non-fan oven the temperature varies significantly in different places; a fan distributes hot air evenly for a uniform temperature.
Convection ovens may include additional radiant heat sources at the top and bottom of the oven, which provide immediate heat without the warmup time of a (natural or fan-assisted) convection oven.
A convection oven allows a reduction in cooking temperature compared to a conventional oven. This comparison will vary, depending on factors including, for example, how much food is being cooked at once or if airflow is being restricted, for example by an oversized baking tray.[ citation needed ] This difference in cooking temperature is offset as the circulating air transfers heat more quickly than still air of the same temperature. In order to transfer the same amount of heat in the same time, the temperature must be lowered to reduce the rate of heat transfer in order to compensate.[ citation needed ]
Another form of convection oven has hot air directed at a high flow rate from above and below food that passes through the oven on a conveyor belt; it is called an impingement oven. [7] [8] [9] This cooks, for example, breaded products such as chicken nuggets or breaded chicken portions faster than a fan oven, and yields a crisp surface texture. Impinged air also prevents "shadowing" which occurs with infrared radiant heat sources. Impingement ovens can achieve a much higher heat transfer than a conventional oven.
Fully enclosed models can also use dual magnetrons, [10] as used by microwave ovens. The most notable manufacturer of this type of oven is TurboChef. The differences between an impingement oven with magnetrons and a convection microwave oven are claimed to be cost, power consumption, and speed. Impingement ovens are designed to be used in restaurants, where speed is essential and power consumption and cost are less of a concern.
There are also convection microwave ovens which combine a convection oven with a microwave oven to cook food with the speed of a microwave oven and the browning ability of a convection oven. [11] [12] [13]
A combi steamer is an oven that combines convection functionality with superheated steam to cook foods even faster and retain more nutrients and moisture[ citation needed ].
An air fryer is a small countertop convection oven that is said to simulate deep frying without submerging the food in oil. [14] [15] A fan circulates hot air [14] at a high speed, producing a crisp layer via browning reactions such as the Maillard reaction. Some product reviewers find that regular convection ovens or convection toaster ovens produce better results,; [16] [17] [14] others say that air frying is essentially the same as convection baking. [18]
The original Philips Air fryer used radiant heat from a heating element just above the food and convection heat from a strong air stream flowing upwards through the open bottom of the food chamber, delivering heat from all sides, with a small volume of hot air forced to pass from the heater surface and over the food, with no idle air circulating as in a convection oven. A shaped guide directed the airflow over the bottom of the food. The technique was patented as Rapid Air technology. [19] [20]
Traditional frying methods induce the Maillard reaction at temperatures of 140 to 165 °C (284 to 329 °F) by completely submerging foods in hot oil, well above the boiling point of water. The air fryer works by circulating air at up to 200 °C (392 °F) to apply sufficient heat to food coated with a thin layer of oil, causing the reaction. [21]
Most air fryers have temperature and timer adjustments that allow precise cooking. Food is typically cooked in a basket that sits on a drip tray. For best results the basket must be periodically agitated, either manually or by the fryer mechanism. Convection ovens and air fryers are similar in the way they cook food, but air fryers are smaller and give off less heat to the room. [15]
There are several types of household air fryer:
In this type, a paddle machine moves throughout the heating chamber to move the air around more evenly. This is more convenient for the user because other types of air fryers require manual stirring throughout to ensure that all sides are fully cooked. [22]
A cylindrical basket is a small, single function air fryer that includes a drawer with a removable basket. A fan circulates from the top, and the food is cooked through holes in the basket. It can accommodate 2.8 litres (3.0 US quarts) of food or less on average. Because of its compact size, it preheats faster than other types of air fryers. [23]
Countertop convection ovens come with an air frying feature that work the same way as basket type air fryers. They usually have multiple trays or racks, so multiple things can be cooked at the same time. It holds 24 litres (25 US quarts) of food on average. They are more versatile than single function type because they have multiple features like baking, rotisserie, grilling, frying, broiling, and toasting. [24]
This type of air fryer cooks food with a halogen radiant heat source from above. The heat is spread evenly with a fan like other types of air fryers. This type is usually a large glass bowl with a hinged lid. [25]
This is a large, barrel-shaped air fryer used to cook whole turkeys and other large pieces of meat. It circulates air around the drum to cook the meat evenly. [26]
Convection ovens have been in wide use since 1945. [27]
In 2006, Groupe SEB introduced the world's first air fryer, under the Actifry brand of convection ovens in the French market. [28] [29] [30] [31]
In 2010, Philips introduced the Air fryer brand of convection oven at the IFA Berlin consumer electronics fair. [32] [33] [20] By 2018, the term "air fryer" was starting to be used generically. [34]
In the United States convection ovens experienced a surge in popularity in the late 2010's and early 2020's with a reported 36% of U.S. households having one in 2020 and an estimated 60% of U.S. households having one in 2023. Food manufacturers have responded by adding air frying instructions on a number of products and pre air-fried products also coming to market. [35] [36]
Industrial convection ovens can be very large.
Hot air ovens are convection ovens used to sterilize medical equipment.
Baking is a method of preparing food that uses dry heat, typically in an oven, but can also be done in hot ashes, or on hot stones. The most common baked item is bread, but many other types of foods can be baked. Heat is gradually transferred "from the surface of cakes, cookies, and pieces of bread to their center, typically conducted at elevated temperatures surpassing 300°F. Dry heat cooking imparts a distinctive richness to foods through the processes of caramelization and surface browning. As heat travels through, it transforms batters and doughs into baked goods and more with a firm dry crust and a softer center. Baking can be combined with grilling to produce a hybrid barbecue variant by using both methods simultaneously, or one after the other. Baking is related to barbecuing because the concept of the masonry oven is similar to that of a smoke pit.
Grilling is a form of cooking that involves heat applied to the surface of food, commonly from above, below or from the side. Grilling usually involves a significant amount of direct, radiant heat, and tends to be used for cooking meat and vegetables quickly. Food to be grilled is cooked on a grill, using a cast iron/frying pan, or a grill pan.
Pressure cooking is the process of cooking food with the use of high pressure steam and water or a water-based liquid, inside a sealed vessel called a pressure cooker; the high pressure limits boiling and creates higher temperatures not possible at lower pressures which allow food to be cooked much faster than at normal pressure.
A microwave oven or simply microwave is an electric oven that heats and cooks food by exposing it to electromagnetic radiation in the microwave frequency range. This induces polar molecules in the food to vibrate and produce thermal energy in a process known as dielectric heating. Microwave ovens heat foods quickly and efficiently because excitation is fairly uniform in the outer 25–38 mm(1–1.5 inches) of a homogeneous, high-water-content food item.
An oven is a tool which is used to expose materials to a hot environment. Ovens contain a hollow chamber and provide a means of heating the chamber in a controlled way. In use since antiquity, they have been used to accomplish a wide variety of tasks requiring controlled heating. Because they are used for a variety of purposes, there are many different types of ovens. These types differ depending on their intended purpose and based upon how they generate heat.
A deep fryer is a kitchen appliance used for deep frying. Deep frying is a method of cooking by submerging food into oil at high heat, typically between temperatures of 350 to 375 °F.
A turkey fryer is an apparatus for deep-frying a turkey. Fried turkey has been a popular item in the Southern United States, and has become popular in other parts of the country because of the reduced time needed to cook a turkey in a deep fryer, versus other conventional methods such as an oven or a rotisserie grill.
Induction cooking is performed using direct electrical induction heating of cooking vessels, rather than relying on indirect radiation, convection, or thermal conduction. Induction cooking allows high power and very rapid increases in temperature to be achieved: changes in heat settings are instantaneous.
A solar cooker is a device which uses the energy of direct sunlight to heat, cook or pasteurize drink and other food materials. Many solar cookers currently in use are relatively inexpensive, low-tech devices, although some are as powerful or as expensive as traditional stoves, and advanced, large scale solar cookers can cook for hundreds of people. Because they use no fuel and cost nothing to operate, many nonprofit organizations are promoting their use worldwide in order to help reduce fuel costs and air pollution, and to help slow down deforestation and desertification.
Sous vide, also known as low-temperature, long-time (LTLT) cooking, is a method of cooking invented by the French chef Georges Pralus in 1974, in which food is placed in a plastic pouch or a glass jar and cooked in a water bath for longer than usual cooking times at a precisely regulated temperature.
The following outline is provided as an overview of and topical guide to the preparation of food:
A masonry oven, colloquially known as a brick oven or stone oven, is an oven consisting of a baking chamber made of fireproof brick, concrete, stone, clay, or cob. Though traditionally wood-fired, coal-fired ovens were common in the 19th century, and modern masonry ovens are often fired with natural gas or even electricity. Modern masonry ovens are closely associated with artisan bread and pizza, but in the past they were used for any cooking task involving baking. Masonry ovens are built by masons.
A susceptor is a material used for its ability to absorb electromagnetic energy and convert it to heat. The electromagnetic energy is typically radiofrequency or microwave radiation used in industrial heating processes, and also in microwave cooking.
Frying is the cooking of food in oil or another fat. Similar to sautéing, pan-fried foods are generally turned over once or twice during cooking to make sure that the food is well-made, using tongs or a spatula, while sautéed foods are cooked by "tossing in the pan". A large variety of foods may be fried.
Combi steamers are combination ovens that expand upon standard convection ovens in that they can also generate conventional moist steam or superheated steam and are capable of shifting between cooking modes automatically during the cooking process. They can be used to simultaneously steam vegetables or potatoes quickly and gently, while also roasting or braising meat and fish, or baking bread. The appliance is fit for many culinary applications, including baking, roasting, grilling, steaming, braising, blanching and poaching. These devices are cooking appliances typically used in professional catering or food service operations. They help gastronomy-industry professionals bridge the gap between economy and menu diversity while also maintaining the desired food quality.
A charbroiler is a commonly used cooking device consisting of a series of grates or ribs that can be heated using a variety of means, and is used in both residential and commercial applications for a variety of cooking operations. The heat source is almost always beneath the cooking surface – for gas-fired applications this is referred to as an under-fired broiler. Most commonly the charbroiler is a series of long evenly spaced metal ribs over a large combustion chamber filled with an array of burners that may have a deflector, briquettes or radiant between the burner and the cooking surface.
A halogen oven, halogen convection oven, or halogen cooking pot is a type of oven that utilizes a halogen lamp as its heating element. Halogen ovens are often noted for being more energy-efficient than a conventional electric oven due to their more effective heating of food and faster cooking times.
June is a home automation company based in San Francisco. Its first product was the June Intelligent Oven, a Wi-Fi-enabled, app-connected countertop convection oven that employs machine learning and computer vision technologies to identify and cook food.