Kevin Banas
November 5, 2015
The Anatomy of a Deep Fryer
The Anatomy of a Deep Fryer

Although not always looked upon with favor by today’s health-conscious gurus, deep frying your food is an ancient method of preparation, dating back to the Roman cookbook, Apicius. The technique was used by nearly all cultures in due time and, by the mid-nineteenth century, the advent of cast iron made it accessible to home cooks. This led to the birth of favorites such as doughnuts, onion rings, and corn dogs. Tasty as these foods may be, they’re not healthy and have the potential to be extremely greasy. Fortunately for us, cast iron is not the final word in deep frying advancements, and with knowledge of how to cook and the help of a few handy technological tricks, deep frying is a viable option for making great food in any establishment.

Understand the How’s of Deep Frying

The first step to selecting a fryer is understanding what you’re going to cook, and how to cook it. Deep frying is the submersion of food in hot oil, typically between 350 and 375 degrees Fahrenheit. Done correctly, this does not have to cause more oil absorption than pan frying might, as natural moisture in the food vaporizes and is expelled outward, preventing oil from entering the food. An appealing brown crust forms on the outside of starchy foods that further protects it from excess oil. For these processes to be reliable, your oil must be hot and you must not overcook the food, as eventually excess oil will seep in. Choose deep fryers that feature timers programmable to your recipes, and most importantly, that have rapid heat recovery.

Gas versus Electric

Many young culinary students are taught that, as a rule of thumb, gas is better in all cooking equipment than electricity, but the truth here is that most electric deep fryers can return your oil to a proper cooking temperature faster and with greater energy efficiency than gas models. The drawback is that they use a lot of power to accomplish this, and local electricity rates or the cost of building an appropriate circuit for them may be prohibitive. Consider models that provide energy efficiency if gas is your preference. Vulcan has released award winning gas deep fryers that use curved heat exchange tubes with interior baffles to slow the progress of burning gas in the heating element, allowing the oil to absorb more heat from the gas.

Oil Quality is Essential to a Quality Product

One obstacle to perfectly fried food is oil quality. Unfortunately most chefs have to rely on their senses (sight, smell, and taste) to tell when the oil needs changing. While you might hold your chef and his palate in high esteem, an executive chef is also a kitchen manager, and his tastes are at odds with the need to extract as much use as possible from the costly oil. Deep fryer oil that has been overused and stretched too far produces inferior quality foods and adds health risks beyond fat content.

Deep fryers help you preserve your oil and extract the most from it chiefly by eliminating crumbs and particles of food shed by the things you’ve previously cooked. The pleasant browning of food mentioned earlier is called the Maillard Reaction. When cooked beyond this initial browning, some foods (particularly starchy ones) can carbonize and seep a burnt flavor into the oil, as well as produce a byproduct chemical called acrylamide, a known carcinogen. Oil further decays when oxygen exposure causes rancidity, or when continuous heating causes polymerization, the process by which hydrocarbon chains break and reform into other chemicals.

Fryer Options

Fryers typically offer two possibilities to slow these processes: A well at the bottom of the fryer where oil is kept relatively cold to allow crumbs to settle in it; or frequent onboard filtration to remove crumbs as they are produced. Some models, such as Frymaster’s latest, offer both. The drawback to the well is that more oil is needed to fill the fryer, while the frequent filtration in some models may leave you periodically unable to cook for a minute or two, which seems reasonable on any night that isn’t Friday. In either design, the periodic addition of small quantities of fryer oil to replace evaporated oil extends the life of the full pot of oil before a complete replacement must happen. Oil dosing systems designed to provide the correct amount at the correct times to achieve this affect can be purchased separate from your fryer, or in some cases, as part of it.

Finally, hand held devices that measure Total Polar Matter (TPM) are the most scientific way of determining when your oil must be discarded. Polar matter includes harmful chemicals as well as polymerized oil, and TPM is frequently measured by testing the electrical resistance of oil. Since the byproduct of expired oil is potentially carcinogenic, European restaurants are required to test and log the TPM of their fryers up to several times daily, and must replace the oil after a certain threshold or be fined. With similar requirements potentially being enacted in the United States, operators should familiarize themselves with these tools not only to safeguard quality, but to remove the guesswork from oil replacement. As of 2015, Frymaster is the only domestic fryer offering onboard TPM measurement in some floor models.

For operators looking for the best way to use an ancient but beloved cooking method, options abound well beyond those presented here. A good foodservice design consultant will guide you in selecting the right equipment to prepare and serve, to dispose of oil, to meet energy efficiency standards, and to delight your guests!

 

By:  Kevin Banas

Associate | Chicago

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