What Exactly Is Air Frying? Ask Paul

Neal asked: “Is there any difference between an air fryer and a convection oven?”

Everybody likes crisp, golden-brown food. Truly. According to groundbreaking food texture scientist Alina Szczesniak, of all food textures, crispness is the one that “appears to be universally liked.” That explains the enormous popularity of the countertop appliance known as an air fryer, whose specialty is crisping up the surface of food. How does it work?

For starters, air frying is not frying, despite the catchy name. It’s a method that emulates some of the crisping advantage of true frying.

Let's start by looking at frying—real frying, using hot oil. Oil can easily heat up to 350 degrees or hotter—much higher than the boiling point of water (212 degrees). 

Because of that, when we drop food (I’m picturing French fries) in hot oil, the heat travels into the food and the water in the outermost layers of the food quickly boils, exits into the oil bath, and bubbles away. Such rapid drying makes the surface get crisp and, as the temperature of the food’s surface rises above 350 degrees, Maillard reactions start, turning it golden and delicious.

Air frying, on the other hand, is a type of convection baking. We’ve touched on this before but in short: In a conventional oven, food is surrounded by hot air as it cooks. Although the air is hot enough to evaporate water, it's a slow process because air can hang onto moisture in a way that oil simply can't. 

As vapor emerges from the food in an oven, it tends to stay close, forming a thin layer of water vapor around each piece of food that insulates it and slows down further evaporation. Eventually, the exterior of baked food will dry out and browning will occur, but the gradual drying of the surface is not conducive to crispness. 

A convection oven—be it a wall oven with convection mode, a countertop convection oven, or an air fryer—addresses this issue by using fans to circulate the air around inside the oven. Moving air continually strips that insulating vapor layer away from the food, allowing the surface to dry faster, heat up faster, and crisp and brown more evenly.

In the early 2000s, a Dutch inventor put together a miniature convection oven designed to maximize crisping of foods with somewhat faster air flow than existing countertop convection ovens. Philips marketed it as the Airfryer, promoting its ability to approximate the crisp brown texture of fried foods without actually frying.

The appliance is nothing more than a countertop convection oven, and not the first, but calling it an “air fryer” turned out to be just catchy enough to bring the joys of countertop convection cooking to a wide audience.

Air frying is typically done in a small oven with a high fan speed, in order to cook the surface of food quickly. The convection mode in an oven does the same thing, though it may have slower airflow than a dedicated air fryer since classic convection ovens are designed more to encourage even cooking than quick crisping. When you buy an air fryer, you’re buying a convection oven. When you eat “air-fried” food, you’re eating baked food. Nothing wrong with that!