There are 3 different types of fryers available to the foodservice operator. These are detailed in their own sections. They are:
- Open Pot
- Flat Bottom
The fryer is an extremely popular kitchen appliance used in about 85% of food service establishments. It is designed to cook foods such as chicken, fish, breaded vegetables, specialized pastries, and of course, the classic French-fried potato. Fryers are available in two major categories: conventional open fryers and pressure fryers.
In its survey of 3,700 eating and dining establishments in the U.S., the National Association of Food Equipment Manufacturers found that commercial food service facilities owned an estimated 792,000 fryers: 59% deep-fat floor models, 27% deep-fat counter models and the remaining 14% were pressure fryers. This study excluded institutional, recreational and retail food service facilities, which would push the figure up to an estimated 1.4 million units.
Electric fryers preheat in 6 to 7 minutes while gas takes 12 to 15 minutes to reach full operating temperature. To operate, set the thermostat to the desired cooking temperature (generally 350°F) and wait until the burners shut off or the signal lights turn off indicating that the fryer is fully preheated.
Many fryers have timers in addition to thermostat controls. Operators need to know the proper temperature and cooking time for each food product. For consistency of quality, these settings must be maintained. Some units are equipped with devices that automatically raise and lower baskets into the fryer at specified times, taking much of the responsibility away from the fryer operator, saving labor and ensuring more consistent quality.
Fry baskets should be loaded to at least one-half of their capacity but never more than two-thirds. Food will not cook properly if the unit is overloaded. After loading, the baskets are lowered into the oil 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.
While deep fat fryers are commonly used to cook French fries they are also good for cooking chicken, shrimp, cheese, mushrooms, and a whole variety of breaded foods.
The cooking medium with all fryers is oil, 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 break down results in better tasting food and longer fat life.
Most fryers have a marker in the fry vessel showing the proper shortening level. Shortening should cover the heating elements and should be level with the top of the submerged fry baskets.
If you use liquid shortening, fill the kettle to the proper level and set the thermostat to the desired temperature. Solid shortening should be first packed solidly around the heating elements. Set the thermostat to 250°F and allow the solid fat to melt slowly or use the automoatic melt cycle found on many electric fryers. Continue to add fat until it reaches the proper level and wait for all the fat to melt before turning up the thermostat to the desired cooking temperature.
The fryer's cooking medium is hot oil, also known as shortening, frying compound or fat. The quality of the final food product largely depends on the quality of this oil. Flavors developed in the oil transfer 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 the oil. These particles continue to cook long after the final food product is removed from the fryer. They can eventually burn, leaving a bitter taste in the oil. Most fryers have a cold zone located at the bottom of the fryer where food particles can collect to minimize this problem. The temperature in this zone is lower than the cooking zone so food particles don't continue cooking. The fryer operator should frequently filter the oil to remove excess food particles and prolong the life of the oil.
Excessive 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 a high temperature tends to cook food faster on the outside and may overcook the outside while leaving the interior portion partially uncooked. On the other hand, cooking too slowly allows the food to absorb more oil making it soggy and adding to food preparation costs.
Electric vs. Gas
As you can see from the graph below, electric out performs gas on preheat which translates to greater recovery.
Note - Preheat is directly proportionate to recovery.
There are many factors to consider when selecting a fryer: first cost, food preparation productivity, ease of operation, heat generation in the kitchen, as well as the energy source used, electricity or gas. Keep in mind that energy only accounts for approximately 3 percent of a 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.
Let's take a closer look at the energy-use issues, remembering that comparisons should be made on the basis of similar equipment where only the energy input is being changed.
Electric frying equipment generally offer these benefits:
- 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.
The most common type of fryer is the open, deep-fat fryer. It comes in a variety of sizes ranging from a counter top model to a large stand-alone unit containing multiple frypots. Fryers have a variety of optional features such as automatic controls, filtration systems, and accessories for holding cooked food.
Another important type of fryer is the pressure fryer. These units are equipped with a special lid designed to keep vapors inside the vessel while cooking. Pressure in the vessel is between 5 and 12 PSI. The fry vessel captures steam driven off of cooked food, increasing the pressure inside the unit until no more moisture is released from the food. This process helps seal in juices, which improves food taste and reduces the amount of oil absorbed by the food. This process also results in shorter cooking cycles, making the unit more productive than open vessel units. Pressure fryers are especially popular for cooking fried chicken.
Specialty fryers are also available for specific needs. One example is the doughnut fryer or flat bottom. This unit has a wide but shallow frypot designed for cooking doughnuts and other fried pastries. The convection fryer is an open vessel design that improves the cooking process by circulating hot oil around the food the way a convection oven circulates hot air.
The most common fryer is the open vat fryer. The portion of the fryer that contains the oil is called the frypot, but it is also known as the fry kettle, vat or fat container. The frypot is usually rectangular ranging from 14 to 18 inches in length 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 for holding 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 allowing the operator to 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 on 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, others have an insulated cabinet. Clearly, the use of some type of insulation reduces energy costs and heat into the kitchen.
Gas fryers have a built in time bomb in that the frypot splits or cracks at some future date (5 to 15 years). The fractures occur from metallurgical degradation due to excessive heating, expansion, and contraction. This action of split pot is a catastrophic condition and is a fire hazard in that hot oil leaks out over live flame. Electric fryers never suffer this problem!
Electric units have heating elements submerged in the bottom of the frypot. These elements are either fixed in position on hinged to the main structure of the fryer. Hinged units can be lifted out of the frypot for easy cleaning. They can be high watt density (calrod) or low watt density (firebar). The low watt density units are more efficient.
Gas units have burners located outside the frypot. Some more advanced units have fire tubes that extend through the frypot and thus 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 portion of the frypot bottom extending below the heat source. The oil in this region 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 where they stop cooking, thereby preventing breakdown of the oil and lengthening cooking oil life. This design also creates a natural convective flow of oil throughout the frypot so that cooler oil continuously recirculates with hot oil. Allowing the oil to cool in this manner reduces breakdown as well.
Nearly all fryers have a thermostat control to maintain the temperature of the frypot. These controls are either located on the front panel or above and behind the frypot. Some units are equipped with a timer that alerts the operator when the food has cooked for a preset amount of time. More sophisticated models have elaborate automatic controls that reduce labor requirements and more closely monitor the cooking process. The automatic basket lift is a prime example. Some units can even be programmed so that the 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.
Some of the better fryers include automatic filtration equipment reducing the labor requirements for daily cleaning. Each manufacturer's system is unique so make sure to follow their specific operating instructions.
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.