In the Deep: Wading Through the World of Deep Fryers


Fried food is getting a bad rap lately as the trend to healthier fare gains attention among today’s consumers, but that doesn’t mean the deep fryer should be given the old heave-ho. Despite what diners say, many are still chowing down on crispy fare, so restaurateurs looking to improve fried offerings and appeal to a wider audience, while maintaining cost and operational efficiencies, should keep up with trends in this equipment category.

Operators of fish and chip or chicken restaurants are often well-versed in the particulars of the average fryer, but in other kitchens the deep-frying station can easily be under-equipped, producing sub-par food.

The key to success is understanding how deep fryers work and what a unit is capable of producing. So, let’s start at the beginning. By definition, deep frying involves the immersion of food in hot oil averaging a temperature of 350°F. The oil transfers heat to the food, causing moisture on the surface to vaporize and forcing the internal moisture to the surface, creating turbulence in the oil as the steam rises. This turbulence, along with the high oil temperature and the loss of moisture, cooks food rapidly, browning it to perfection.

An operator can expect to pay from $1,000 for the most basic 35-lb gas fryer to $6,000 for one with all the bells and whistles. Meanwhile, the premium for electric units can be anywhere from 35 to 50 per cent of the cost of a similar gas-powered unit.

The Source

In almost all cases fryers are powered by one of three energy sources: gas, liquid propane or electricity.

Gas fryers can be divided into two categories, standard and high-efficiency. The more common standard fryers incorporate burners, which tend to be inefficient since up to 70 per cent of the heat generated can be lost in the flue. High-efficiency units take advantage of innovations in gas technology such as infrared burners, tubes with baffles and pulse combustion — reducing energy output by as much as 30 per cent.

Electric fryers, on the other hand, are almost 90-per-cent energy efficient, and innovations such as induction coils and low watt-density elements have made such units a more viable choice. On the downside, electrical energy costs more than gas in most parts of the country.

Choosing the Right Fit

Deep fryers are available in a range of sizes and configurations, from small countertop units to large floor models and banks of several units in one assembly. Choosing the right unit comes down to understanding particular needs. In other words, a fryer is rated by the number of pounds of oil it can hold (30, 45, 50, 55, et cetera) and the energy input calculated as BTUs (British Thermal Units) for gas or liquid propane and kilowatts per hour (kWh) for electric. These figures allow the manufacturer to calculate the amount of food that can be cooked in a period of time. As a comparison, most calculations are based on how many pounds of french fries can be cooked in a one-hour period.

Any basic fryer should bring the oil to a preset temperature, maintain the temperature and restore the oil to the preset temperature when food is introduced. Almost all fryers perform the first two functions adequately, but the third function, called recovery time, can often be a problem. In the case of the latter, the temperature of the oil will drop relative to the amount and temperature of the product being cooked. If the temperature drops drastically, and does not return to optimal cooking temperature in reasonable time,

the food’s moisture won’t be efficiently vaporized, and oil will seep into the food. Simply put, the quality of the food will be compromised, and the life of the oil will be shortened.


When calculating the production capacity required for fryers, operators need to consider the type of products being cooked and peak demand times. Since most cooks turn the fryers on in the morning, and keep them idling at a preset temperature all day, it can be more cost efficient to have two smaller units instead of one larger unit. This way, one machine can be used regularly, while the second can be used during peak periods, reducing overload and speeding up recovery time.

In most high-volume restaurants operating at peak demand, fryers are almost constantly full, and the overall quality of the finished product can be severely affected if the fryer’s speed of recovery is inadequate. A quick recovery time is critical when frying frozen products as they will decrease the oil temperature more dramatically than foods at room temperature, but overloading is not the answer — doing so ultimately costs more. Instead, an operator should calculate the number and size of fryers required to prepare the amount of food needed.

Open-pot Fryers

The most common type of fryer is called an open pot, which holds between 15 and 200 pounds of fat. Most operators specify a 35- to 50-pound kettle capacity as it gives the best value. In this case, the food is loaded into baskets and immersed in the hot oil for cooking using gas, liquid propane or electricity.

In an open-pot vessel, a thermostat indicates the temperature of the oil and a valve or electrical contact is closed when the preset temperature is reached. Thermostats can be bulb-type sensors filled with fluid that expand when heated or more expensive solid sensors, which are often more accurate and reliable.

No matter what type of thermostat is used, it should be positioned in the centre of the vessel so it can react to loads being dropped on either side, quickly returning the oil to the preset temperature.

Open-pot vessels are available in lightduty and heavy-duty format, with the difference being the BTU output will determine recovery time. If small amounts of foods are being cooked sporadically, a light-duty fryer is adequate; cooking large quantities in a short period requires a heavy-duty quickrecovery unit. The other major difference between a light- and heavy-duty unit is the quality of manufacturing material and components: a light-duty unit may be cheaper, but the extended life and efficiency of a heavy-duty unit will pay dividends.

Pressure Fryers

A pressure fryer is a vessel fitted with a lid and pressure valve. As the moisture in the food is vaporized, it is contained within the vessel where pressure rises, causing moisture in the food to reach higher temperatures, reducing cook time and moisture loss. Since food cannot be checked during the cooking process, these units are generally confined to operations with limited menus and standardized procedures such as quick-service restaurants, specializing in fried chicken.

Specialty Fryers

These units have a large, shallow rectangular vessel with a large surface area and a deep cold zone. Mostly used for doughnuts or chicken, where the product is lowered into the oil on a screen rather than a basket, these machines allow room for the food to float as it cooks.

Air Fryers

Air fryers or oil-less fryers are a recent innovation in fryer technology and have become popular at small operations and concession stands. Countertop air fryers use hot convection air, rather than hot oil, and since there is no open flame, no mechanical ventilation and fire protection is necessary. As a bonus,

the finished product is said to be healthier and less greasy. On the downside, the texture and flavour of the finished product falls short and production capacity is significantly less than conventional units.

Ventless Fryers

Speaking of innovation, the introduction of the small, self-contained countertop electric fryer is winning attention, too. The ventless unit is useful at concession stands and snack bars where a traditional cooking line, with fire protection and mechanical ventilation, is not available or expensive to install.

Countertop fryers operate on the same principle as conventional fryers: an electrical element submerged in the oil provides the heat, while baskets hold the food.

These units operate on either 120- or 240-volt connections and require 15 to 30 amps of power. The cooking and recovery times will depend on the power input, and since fryer capacity is quite limited — with about eight litres of oil accommodated in the vat — the production output is limited. For example, it

will take two to three minutes to cook one to one and a half pounds of french fries on a ventless unit, therefore it would be the ideal fryer for operators looking to increase menu offerings without incurring significant expense.

Although countertop fryers operate without vents, anyone considering installing one should check local fire-protection regulations, which vary from city to city.

Moving on, floor models are the newest innovation in ventless fryers. The open-pot and pressurized format is available in 30- and 55-lb capacity in gas and electric models with built-in oil-filtering systems. These units have an integrated hood with an air filter and fire-suppression system built directly onto

the fryer. Although emissions and odours are minimal, the units do require sufficient air exchange and a minimum of six feet of floor clearance. This configuration allows the operator to achieve the same capacity and product quality as a comparable traditional fryer in areas where traditional mechanical ventilation systems are not practical. These units range in price from $17,000 to $20,000.

Clean Sweep

To get the most out of a fryer, filter the oil and clean the crackling and debris from the bottom of the vessel. Most manufacturers offer an integrated filtering system option in their fryer lineup, which usually consists of an additional module alongside the bank of fryers to pump the oil through a filtering system and back into the kettles. For operators with limited space, newer models integrate the filtering system into the bottom of the fryers, reducing its footprint.

When all is said and done, it’s important to assess needs accurately and explore the options available to make an informed and intelligent purchase decision.

Vendor Information

Check out the cheatsheet below for the names and coordinates of a couple of deep-fryer vendors:

For a complete supplier’s list, check the Buyer’s Guide.

More in Feature Articles:

Start me Up: Uncovering What’s Big in Small Plates

Notable Potables: Bar Report

Building an Empire: Profiling Lidia Bastianich

What’s Next for Grant Achatz and Nick Kokonas

A Helping Hand: Ontario Greenbelt Fund Announces New Grants

Hospital Makeover

Straight Shooter: Profiling Chef Neil Taylor

From the Editor: Fall Flurry

This site uses Akismet to reduce spam. Learn how your comment data is processed.