The Science of Frying

Frying is such a common technique in cooking that you would be forgiven for just doing it without thinking about why it works. But why does it work? Why does it make things so crispy on the outside and gooey on the inside? And what’s the best way to make it work? 

We’re going to walk you through the basics so that next time you dunk some breaded chicken in hot La Española Mild & Light Olive Oil you can understand exactly what’s happening underneath the crispy surface.

The Maillard Reaction

To understand the science of frying, you must first understand the work of Louis Camille Maillard. In 1912 he published a paper describing the reaction between amino acids and sugars at high temperatures. 

While humans had been cooking their food for literally millennia before Maillard came along, he was the first one to study and write down why cooking makes the food taste good. And he did such a good job at it that we named the process after him. The Maillard Reaction is many small, simultaneous chemical reactions that occur when proteins and sugars in and on your food are transformed by heat, producing new flavors, aromas, and colors.

The Maillard Reaction is not specific to frying, although it plays a huge role in it. In fact, the Maillard Reaction is what gives bread its crust, steak its char, and coffee beans their robustness. Even beer sees the Maillard Reaction when the grains used to brew it are roasted beforehand! 

We still don’t entirely understand what happens during a Maillard reaction, but what we do know is that, given the right amount of heat, time, and moisture, sugars and proteins will react together and produce delicious, complex flavors, aromas, and melanoidins. (Melanoidins are molecules that give food their browned color.)

Time to Fry

Frying is a specific way to invoke the Maillard reaction in which you cook your food in hot liquid fat. Without the hot fat, the reaction happens only where the food touches the hot surface. With the fat, the heat is distributed through all the little bumps and crevices on the food’s surface. So, why does liquid fat make a crispy French fry and not, for example, water? 

The Maillard Reaction actually works through the amino acids in the fat to dehydrate the surface of the food and create a sort of barrier to block any of the fat from being absorbed by anything beneath the surface. That dehydration produces the signature crispy crunch that makes frying so delightful.

Meanwhile, heat is still being conducted into the middle of the food to gelatinize starches, denature proteins, or soften fibers just like it would be through any other cooking method. That dehydrated surface is protecting the moisture underneath, causing the insides to steam. When you’re done frying, the insides continue to steam, and as long as you can see that steam rising from your food, you know that crisp coating is doing its job right. When it stops steaming, the interior moisture will start to be absorbed into the coating, making it soggy. That’s why it’s always best to eat fried foods as soon as you can handle the heat!

What’s the Best Frying Oil?

It depends on what is important to you about olive oil. Depending on your choice you could use your oil for longer, extract more flavor from it, or be more health-conscious. It’s all contingent on the oil’s level of hydrogen saturation. Saturated fats like animal fat are considered very flavorful but are also less healthy since they are associated with a higher risk of cardiovascular disease. They also have a very low smoke point, which means when they reach a certain temperature (350°F to 375°F), they start releasing free radicles and fatty acids that burn and create a visible smoke that ruins the flavor of your food. 

We recommend La Española Light & Mild or La Española Grape Seed Oil. Not only will they work at higher temperatures (410°F to 445°F), but they won’t overwhelm the natural flavor of your foods, and their polyunsaturated fats will make your food more healthful.

Now go out and fry like a pro!