Deep fat fryer
Encyclopedia
While commonly used in commercial kitchens, household models are available and have become common.
Features
Modern fryers feature a basket to raise food clear of the oil when cooking is finished. Fryers often come with features such as timers with an audible alarm, automatic devices to raise and lower the basket into the oil, measures to prevent food crumbs from becoming over cooked, ventilation systems to reduce frying odors, oil filters to extend the usable life of the oil, and mechanical or electronic temperature controls. Deep fryers are used for cooking many fast foods, and making them crispy.Construction
The modern commercial fryer boasts improved energy efficiency due in part to better heat transfer systems. Commercial fryers with infrared heating or convection heatingConvective heat transfer
Convective heat transfer, often referred to as convection, is the transfer of heat from one place to another by the movement of fluids. The presence of bulk motion of the fluid enhances the heat transfer between the solid surface and the fluid. Convection is usually the dominant form of heat...
are efficient, but often expensive. The most common fryer models are electric and gas.
Electric restaurant fryers are popular in counter top models because of their mobility. They lose a little less heat than gas fryers because their heating elements are immersed in the oil, and they have a faster temperature recovery time between frying cycles. Gas fryers heat up more quickly and to a higher cooking temperature than electric fryers. Gas fryers can be powered by either natural gas or propane, both of which are generally less expensive energy sources than electricity. This makes gas power especially popular in floor model fryers.
Commercial fryers are generally available in mild steel or stainless steel
Stainless steel
In metallurgy, stainless steel, also known as inox steel or inox from French "inoxydable", is defined as a steel alloy with a minimum of 10.5 or 11% chromium content by mass....
. Stainless steel is less likely to corrode or stain than mild steel. Mild steel also expands under heat which may damage the welds over time. Because of this, stainless steel fryers often come with a much better warranty than mild steel fryers.
Fryers are available with a variety of fry pot styles. Some commercial fryers have a “cold zone” at the bottom of the fry pot. This is where larger food particles sink and the lower temperature keeps them from burning and tainting the oil. A tube-style fry pot has a large cold zone because the tubes are slightly above the bottom of the vat, leaving generous space for cooler oil and crumbs. This is particularly useful for cooking heavily breaded foods (such as a blooming onion
Blooming onion
A blooming onion, onion bloom, onion blossom, or onion 'mum is a dish consisting of one large onion which is cut to resemble a flower, battered and deep fried. It is served as an appetizer at some restaurants....
). A tube-style fry pot is more difficult to clean than an open fry pot, but the tubes allow easy access to the heat source. Tube fryers are often a little less expensive than their open fry pot counterparts. Open fry pots have an external heat source, which makes them easier to clean and affords better access to the oil, but they generally offer a smaller cold zone, so food particles that sink could scorch and pollute the flavor of the oil. However, these fryers work very well for lightly breaded foods. Flat-bottomed restaurant fryers—another type of open frypot fryer—can also be difficult to clean and have no cold zone, but they are highly effective for frying dough (such as donuts or funnel cakes).
Temperature controls
Many of the new fryer models include electronic temperature controls. These computerized controls save energy by constantly sensing and adjusting the temperature of the oil. A high quality thermostatThermostat
A thermostat is the component of a control system which regulates the temperature of a system so that the system's temperature is maintained near a desired setpoint temperature. The thermostat does this by switching heating or cooling devices on or off, or regulating the flow of a heat transfer...
can stay within a 7.2 ˚C range of a desired temperature, assuring accurate cook times. Safety thermostats that automatically cut the power if the oil reaches dangerous temperatures help prevent oil fires.
Oil filtration
An oil filtration system, chemical treatment, or diatomaceous earthDiatomaceous earth
Diatomaceous earth also known as diatomite or kieselgur/kieselguhr, is a naturally occurring, soft, siliceous sedimentary rock that is easily crumbled into a fine white to off-white powder. It has a particle size ranging from less than 1 micrometre to more than 1 millimetre, but typically 10 to...
powder all help remove tiny food particles that are not always visible. Using these systems doubles the life of the oil. Oil filtration systems can sometimes be purchased as an enclosed part of the fryer to avoid involving employees in the somewhat dangerous process of filtering the oil with an exterior system. Many restaurants use a portable oil filtration system or a “shortening shuttle” to transport waste oil to a disposal area. However, even old oil is not completely useless. There are ways (involving other chemicals and machinery) to “recycle” old oil as biodiesel
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
that can power diesel vehicles.
Accessories
Restaurant fryers are available with a wide array of accessories and options. There are countertop models, single floor models, and “fryer batteries” with multiple floor fryers, a filtration system, and holding stations all built together as one large floor fryer system. Individual fryers may have one or more tanks. Commercial floor-model fryers can be fitted with casterCaster
A caster is an undriven, single, double, or compound wheel that is designed to be mounted to the bottom of a larger object so as to enable that object to be easily moved...
s for easier maintenance and cleanup. Fry baskets also come in various shapes and sizes, from taco salad bowls to onion loaf baskets, with or without heat resistant handles.
Automated deep fryers
Industrial enterprises producing deep-fried snackSnack
A snack is a small portion of food eaten between meals. The food might be snack food—items like potato chips or baby carrots—but could also simply be a smaller amount of any food item.-Snacks and health:...
foods such as potato chips or pre-fried French fried potatoes use automated frying systems that consist mainly of the actual frying pan, a tube type heat exchanger
Heat exchanger
A heat exchanger is a piece of equipment built for efficient heat transfer from one medium to another. The media may be separated by a solid wall, so that they never mix, or they may be in direct contact...
to heat the frying oil, a filter, a circulation pump, a banana tank for fresh oil and the automation system, most often a PLC
Programmable logic controller
A programmable logic controller or programmable controller is a digital computer used for automation of electromechanical processes, such as control of machinery on factory assembly lines, amusement rides, or light fixtures. PLCs are used in many industries and machines...
. As the product leaving the fryer contains a percentage of oil (in potato chips approx. 35%) there is a constant flow of fresh oil into the system. Sensors for the temperature of the oil, the oil level, different pressures in the system and other parameters are used as input for the PLC.
Fire risks
Deep fryers malfunctioning or being used inappropriately are a serious fire risk. Furthermore, putting water on oil fires will cause a fire boiloverBoilover (fire)
A Boilover type of fire refers to an extremely hazardous situation where an attempt is made to extinguish semi-enclosed oil or petrochemical fueled fire with water. The hazard results due to the difference in density between oil and water...
and aggravates the situation. There are special fire extinguishers for food oil fires.
Domestic fryers often include a safety cut-out in case of overheating, for example if not enough oil is used or the fryer is switched on whilst empty. A reset button is included on most of these fryers to reset the safety device once the unit has cooled down; if a reset button is not included the fryer may need repairing if the safety device activates.
See also
- Chip panChip panA chip pan is a deep-sided cooking pan used for deep-frying. Chip pans are named for their traditional use in frying chips ....
- SautéingSautéingSautéing is a method of cooking food, that uses a small amount of fat in a shallow pan over relatively high heat. Ingredients are usually cut into pieces or thinly sliced to facilitate fast cooking. The primary mode of heat transfer during sautéing is conduction between the pan and the food being...
- Set-n-Forget cookerSet-n-Forget cookerThe Set-n-Forget deep fryer was designed by the influential Australian racing car designer John Joyce of Bowin Cars fame. In the early 1970s when the demand for racing cars declined in Australia, the Bowin Car company was forced to change its direction from Formula racing cars to commercial goods...
- Vacuum fryerVacuum fryerA vacuum fryer is a deep-frying device housed inside a vacuum chamber. It was originally developed for potato chip production.Vacuum fryers are fit to process low-quality potatoes that contain higher sugar levels than normal, as they frequently have to be processed in spring and early summer before...