One of the biggest appeals of an air fryer is that it can create a browned, crispy surface with relatively little added oil. However, this doesn't mean it works exactly like frying in a lot of oil, and the results won't be the same for every dish.

A well-known chemical process plays an important role in the development of browned crusts and characteristic “fried” flavors: the Maillard reaction . This same reaction contributes to the color, aroma, and flavor of bread crusts, browned meats, and many fried foods, among other things.

This process is beneficial for the air fryer because the high-velocity hot air helps to heat and dry the surface of the food. If the temperature, cooking time, and surface moisture are right, more intense browning can occur.

What happens during the Maillard reaction?

The Maillard reaction is a series of complex chemical reactions in which amino groups in foods, such as those from amino acids and proteins, react with reducing sugars.

During the process, many new compounds can be formed that contribute to:

• to brown food;
• for the development of toasted, fried aromas;
• and for more complex flavors.

That is why we encounter the effects of the Maillard reaction, for example, when baking bread, browning meat, roasting coffee, or frying potatoes.

It does not “turn on” at a single temperature

We often come across the simplification that the Maillard reaction begins around 140 °C. The reality is more complex than that.

The reaction can also occur at lower temperatures, but at a much slower rate. It usually speeds up as the temperature increases, making it much more visible during baking and roasting.

The speed of the process is determined by several factors:

• temperature;
• baking time;
• surface moisture content;
• pH;
• and the amount and type of amino acids and reducing sugars in the food .

Why is a drier surface important?

When cooking in water, the surface of the food typically remains much wetter, making it more difficult to create the conditions necessary for spectacular browning. At atmospheric pressure, the temperature of liquid water remains around 100 °C during boiling, while evaporation removes significant heat.

During baking, on the other hand, the surface water can gradually evaporate. As the surface becomes drier and warmer, conditions become increasingly favorable for browning reactions.

An air fryer is more like a convection oven: it circulates hot air intensively around the food , which can help dry and brown the surface.

Microwave or air fryer: why will the surface of the food be different?

The microwave and air fryer deliver energy to food in completely different ways, so the end results may differ.

A microwave oven heats food using an electromagnetic field. Microwaves interact primarily with polar molecules and dissolved ions, which generates heat in the food.

This does not mean that the microwave simply cooks the food “from the inside out.” Microwaves penetrate the food to a certain depth, and the heat generated spreads further within the material.

However, with traditional microwave cooking, the surface of the food tends to remain wetter and there is no intense, hot air flow around it to dry it out quickly. As a result, the conditions required for browning and crispy crust formation are less favorable .

Of course, the situation may be different for microwave ovens equipped with a grill function or a special toasting surface.

What does the air fryer do differently?

An air fryer is essentially a compact, electric oven with intensive air circulation. The heating element heats the air, and the fan circulates it around the food at high speed.

This has two important consequences:

• hot air quickly transfers heat to the surface of the food;
• and at the same time promotes the evaporation of surface moisture.

As the surface becomes drier and warmer, more favorable conditions may develop for the Maillard reaction and other browning processes.

This is why the surface of potatoes, meat or breaded food cooked in an air fryer can become browned and crispy much more easily than when heated in a traditional microwave.

An air fryer doesn't fry in the same way as a lot of oil

The end result may be similar to frying in plenty of oil for certain foods, but the heat transfer of the two processes is not the same.

When frying in oil, the hot oil directly surrounds the food and transfers heat to its surface very efficiently. In an air fryer, this task is primarily performed by the hot air flowing at high speed.

Therefore, the consistency and browning achieved with an air fryer depends on:

• from the raw material;
• from surface moisture;
• the baking temperature and time;
• from the flow of air;
• and whether we use little added oil.

The air fryer is therefore not a frying pan without oil , but rather a different heat transfer method that can create a similarly browned, crispy surface for certain foods.

How do the different baking methods differ?

Why does humidity matter so much?

Surface moisture is one of the most important factors in browning. As long as there is a lot of water on the surface of the food, a significant portion of the energy input is used to heat and evaporate it.

As the surface dries, it can reach higher temperatures and the tanning reactions can accelerate.

This is why overcrowding your air fryer can be a problem. If you put a lot of wet ingredients in the basket at once, more water vapor is created, and it is harder for the air to circulate around the individual pieces. The result can be less even browning and a softer surface.

How can we help with browning in an air fryer?

The air fryer can create good conditions for browning, but the final result is also greatly influenced by the preparation of the ingredients.

The most important considerations are surface moisture, free air flow, cooking temperature, and how evenly the food receives heat.

Reduce excess surface moisture

For certain ingredients – such as meat or freshly washed potatoes – it may be beneficial to remove some of the water remaining on the surface before frying.

A surface that is too wet will heat up more slowly to a range favorable for tanning because the energy input is first used to heat and evaporate the water.

Therefore, if the recipe allows it, it may be worth draining the ingredients or carefully wiping them dry before baking.

However, not all foods require a completely dry surface. For foods that have been marinated, breaded, or have a higher moisture content, other considerations may be important.

A little oil can improve the browning of the surface

One of the advantages of an air fryer is that it can be used to prepare many dishes with much less added fat than when frying in plenty of oil.

For certain materials, a thin layer of oil:

• it can help coat the surface more evenly;
• can improve heat transfer on the outer layer;
• and can contribute to a more even blush.

However, it is not necessary to add oil to every dish. It is often not necessary for pre-oiled, naturally fatty or frozen products that are ready to fry.

When using oil, it is generally best to aim for a thin, even coating , not a large amount.

Do not obstruct the air flow.

One of the keys to how an air fryer works is that the hot air can circulate the food properly.

If the basket is overcrowded:

• the pieces can contact each other over a larger surface area;
• less air reaches all sides;
• and more moisture may accumulate in the cooking compartment.

This may result in uneven browning and a less crispy surface.

For larger quantities, baking in several batches can often yield better results than filling the basket completely.

Turn or shake during baking if necessary

The airflow is not exactly the same in all air fryers and not in all basket positions.

For potatoes, vegetables, and foods cut into smaller pieces, it can be helpful to turn or shake the contents of the basket once or more during cooking.

This exposes new surfaces more directly to the hot air flow, which can result in more even browning.

Higher temperatures are not always better

Browning reactions generally occur faster at higher temperatures, but this does not mean that all foods should be cooked at the maximum temperature of the appliance.

At too high a temperature, it may happen that:

• the outer layer browns too quickly;
• while the interior is not yet properly finished;
• or the food will dry out before it reaches the desired consistency.

For better results, it is therefore worth finding a balance between temperature and baking time that suits the given ingredient .

The downside of tanning: the issue of acrylamide

The Maillard reaction can create desirable flavors and colors, but in some foods it can also produce compounds that should be consumed in limited amounts. These include acrylamide .

Acrylamide can form mainly in starchy foods – such as potatoes, bread and some cereal products – at high temperatures and lower moisture levels.

Reducing sugars naturally present in food and the amino acid asparagine play an important role in its formation. The process typically becomes more significant when baking, browning, and roasting above 120 °C.

Therefore, from the point of view of acrylamide, it is not the decisive issue whether we use an air fryer, an oven or a deep fryer . It is much more important:

• what kind of ingredients we bake;
• at what temperature;
• how long;
• and to what extent we brown it.

Therefore, an air fryer alone does not guarantee lower acrylamide formation. For example, if potatoes are fried at high temperatures for too long and browned too much, significant amounts can be formed in this appliance as well.

Golden yellow, not dark brown

When cooking potatoes and other starchy foods, a good rule of thumb is not to aim for the darkest browning possible .

With more intense browning, the potential for acrylamide formation generally increases, so when frying potatoes, it is best to aim for a golden or lighter color and avoid dark brown, burnt parts.

However, the right temperature varies from food to food. It is not worth stating as a general rule that, for example, 180 °C is the ideal setting in all cases .

It is especially worth following when it comes to potatoes:

• the preparation instructions of the appliance or food manufacturer;
• monitor the color change during baking;
• and bake only until desired consistency and light golden brown color is achieved.

Setting the air fryer's precise temperature and time can help with this, but for the right results, it's still worth paying attention to the food itself, not just the numbers on the display.

Why is it useful to understand what happens during baking?

There is no special trick behind how an air fryer works: the device circulates hot air at high speed around the food, while the surface gradually loses moisture and heats up.

If we understand how the Maillard reaction is related to this, it will be easier to recognize why it matters so much:

• surface moisture;
• the right temperature;
• the baking time;
• free flow of air;
• and the little oil added to certain foods.

In practice, this helps us not to rely solely on a preset program, but to adapt the cooking to the specific dish.

For example, if your potatoes aren't browning properly, it's not necessarily a problem with the appliance's performance. It could be that the ingredients are too moist, too many were put in the basket at once, or simply that a different temperature and cooking time would be appropriate.

The same is true the other way around: higher temperatures do not automatically mean better results. The goal is to achieve the right balance between internal browning, surface browning, and desired texture .

However, choosing the right air fryer is only the first step: for a good end result, it is just as important to use the device correctly for the given dish.