Used in about 85% of food service establishments, fryers are an extremely popular commercial cooking appliance. A fryer is designed to cook chicken, fish, breaded vegetables, specialized pastries, French-fried potatoes, and other foods.
Two major types of fryers are available:
Conventional open fryers.
The most common fryer type is the open, deep-fat fryer. These come in many sizes ranging from counter top models to large stand-alone units with multiple frypots. The fryers have a variety of optional features such as automatic controls, filtration systems, and accessories for holding cooked food.
These units have a special lid that keeps vapors inside the fry vessel. The vessel captures steam from the cooking food, increasing pressure inside the unit to prevent additional moisture from being released from the food. This seals in juices, improving food taste and reducing the oil absorbed by the food. The also produces shorter cooking cycles, making pressure fryers more productive than open fryers. Pressure fryers are especially popular for cooking fried chicken.
Besides these two major fryer types, specialty fryers are also available for special needs. One example is the doughnut fryer, which has a wide, shallow frypot designed for cooking doughnuts and other fried pastries. Another example is the convection fryer, which is an open vessel design that improves cooking by circulating hot oil around food in much the same way as a convection oven circulates hot air.
Comparing Electric vs. Gas Fryers
There are many factors to consider when selecting a fryer: initial cost, food preparation productivity, ease of operation, heat generation in the kitchen, and whether electricity or gas is used as the energy source. However, consider that energy only accounts for 3 to 5 percent of a typical food service establishment's total costs. Therefore, while one fuel may be less expensive in a BTU to BTU comparison, the best choice in cooking equipment is the one that minimizes total operating costs, not just energy costs. Features that reduce labor costs or result in higher food product yield will nearly always outweigh any energy considerations. Make sure that you include all of these factors in any equipment evaluation.
Therefore, when comparing gas an electric models, compare equipment that is similar in all ways except the energy source.
Advantages of Electric Fryers
In general, electric frying equipment offers these advantages:
- The electric heating elements operate at lower temperatures, which saves energy, reduces fat breakdown, and uses less fat. Gas burners can create hot spots in the fryer, which breaks down the oil prematurely.
- Electric fryers add less heat to the kitchen because they are more energy efficient.
- Electric units require less maintenance and require less ventilation.
- Electric units have faster preheat and recovery times than gas units.
- Electric induction units are now available that use magnetic induction coils to heat the oil. Some electric fryer manufacturers are also using lower watt-density elements to improve efficiency and achieve longer oil life.
Energy and Money Saving Tips
Here are a few common-sense operating tips that save money with a fryer.
- Turn the fryer off or down to an idling temperature during slack periods when the unit is not in use.
- Operate the fryer at the proper temperature, 325° to 350°F. Excessive temperatures waste energy and often result in improperly cooked food.
- Do not load the fryer baskets beyond the manufacturer's recommended capacity. This is usually one-half to two-thirds full. Overloading results in poor food quality.
- Check fat levels frequently. Low fat levels can cause premature oil breakdown.
- Drain and strain the oil frequently. This saves oil and preserves food quality.
- Keep the units clean and properly maintained.
The most common fryer is the open vat fryer. The portion of the fryer that contains the oil is called the frypot (also called the fry kettle, vat or fat container). The frypot is usually rectangular and ranges from 14 to 18 inches long by 18 inches wide and 18 inches deep. Wire baskets containing uncooked food are lowered into the frypot for cooking. Next to the frypot are supports that hold the wire baskets while cooked food drains excess oil back into the frypot. Some units have a removable frypot while others have frypots that are fixed in place.
Some frypots are split into two sections so the operator can cook two different kinds of foods without transferring taste. In addition, the operator can turn off one side of the unit during slow periods. This saves energy costs and prolongs oil life.
Most fryers have a 1- to 3-inch separation between the frypot and the outer housing or cabinet. Some units have insulated frypots, while others have an insulated cabinet. The use of insulation reduces energy costs and heating up of the kitchen.
Electric units have heating elements submerged in the bottom of the frypot. These are either fixed in position or hinged to the main structure of the fryer. Hinged units can be lifted out for easy cleaning.
Gas units have burners located outside the frypot. Some more advanced units have fire tubes that extend through the frypot in order to transfer more heat to the oil. These fire tubes often contain baffles to improve heat transfer and reduce the amount of heat wasted by escaping up the flue.
Most fryers have a cold zone, which is a small section of the frypot bottom extending below the heat source. The oil in this section is intentionally cooler than the oil in the cooking zone. When particles of food, batter, and breading escape from the basket, they sink to the bottom and collect in the cold zone and stop cooking, which prevents oil breakdown and lengthens cooking oil life. This design also creates a natural convective flow of oil throughout the frypot so cooler oil continuously recirculates with hot oil. Allowing the oil to cool in this way further reduces breakdown.
Nearly all fryers have a thermostat to maintain the temperature of the frypot. This control is either located on the front panel or above and behind the frypot. Some units also have a timer that alerts the operator when the food has cooked for a preset amount of time. More sophisticated models have elaborate automatic controls, such as an automatic basket lift, that reduce labor requirements and more closely monitor the cooking process. Some units can even be programmed so an operator only needs to specify the food type, such as French fries, and the unit automatically controls the cooking time and temperature. This reduces training costs and improves product quality.
Better fryers include automatic filtration equipment that reduces the labor requirements for daily cleaning.
Fryer Operation Tips and Issues
Most fryers take between 5 and 15 minutes to reach full operating temperature. Typically, a signal light stays on when the temperature is below the set temperature point. Operators set the thermostat to the desired temperature and wait till this light turns off, indicating the fryer is ready.
Many fryers have timers as well as thermostat controls. Operators need to know both the proper temperature and cooking time for each food product. For consistency of quality, these settings must be maintained. To address this need, some units have devices that automatically raise and lower baskets into the fryer at specified times, taking responsibility away from the operator. This saves labor costs and ensures more consistent quality.
Fry baskets should be loaded to at least one-half of their capacity but never more than two-thirds, because food does not cook properly if overloaded. After loading, a basket is lowered into the fat and the timer started. For automatic units, the baskets are attached to the automatic elevator supports and with the press of a button the frying process begins.
At the end of the recommended cooking time, the baskets are lifted out of the oil bath and hung on basket supports for draining. Automatic units are programmed to do this without operator assistance.
During slack periods, the fryer should be turned off or its temperature turned to a 200 degree standby setting. This saves energy and increases the life of the fat.
Finally, all units should have a safety thermostat to warn the operator when the temperature exceeds 400°F. Some models have a warning light that turns on or flashes when the unit overheats. If this occurs, the unit should be turned off and allowed to cool. If the unit overheats again, it should be serviced.
The cooking medium for all fryers is oil (also called shortening, frying compound, or fat), which is heated to about 350°F. The oil is typically vegetable or animal fat purchased in solid or liquid form. Top grade commercial shortening with a high smoke point and resistance to breakdown results in better tasting food and longer fat life.
Most fryers have a marker in the fry vessel that shows the proper shortening level. In units without a marker, shortening should cover the heating elements by at least one inch .
If you use liquid shortening, fill the kettle to the proper level and set the thermostat to the desired temperature.
For solid shortening, first pack the shortening solidly around the cooled heating elements. Next, set the thermostat to 250°F to let the solid fat melt slowly. Continue to add fat and wait for it to melt until it reaches the proper level before turning the thermostat up to the desired cooking temperature.
The quality of the final food product largely depends on the quality of the oil that is used. Flavors develop in the oil transferred to the foods being cooked. Also, oil is expensive, ranging from 30 to 75 cents per pound. Since a single fryer's oil capacity can range from 28 to 110 pounds, the cost for replacing used oil can be significant.
Food particles eventually degrade oil. Particles continue to cook long after the food is removed from the fryer, and can eventually burn, leaving a bitter taste in the oil. To minimize this problem, most fryers have a cold zone at the bottom of the fryer where food particles collect. The temperature in this zone is lower than the cooking zone, so food particles stop cooking. However, the fryer operator should still frequently filter the oil to remove excess food particles and prolong the life of the oil.
Excess temperature can also destroy cooking oil. If the fryer's temperature exceeds 400°F, the oil will begin to break down and develop a bad taste. Thermostat overrides and hot spots along burner tubes in gas fryers are frequent culprits.
Cooking temperature also greatly affects the quality of the final food product. Cooking at too high a temperature may overcook the outside of food while leaving the interior portion partially uncooked. However, cooking at too low a temperature causes food to absorb more oil, which makes it soggy and adds to food preparation costs.
For more information about the benefits of electric fryers vs. gas, please contact us for a copy of an EPRI performance or ventilation report.