Want the Creamiest Mac and Cheese? Buy American.

Heat them, and their fragile emulsion (a fat-moisture network held together by proteins) breaks down into a greasy, curdled mess: not exactly the texture you’re aiming for in a creamy pasta dish.

Mac and cheese recipes typically get around this breakdown by stabilizing the cheese with a béchamel, the classic French white sauce made by cooking flour in melted butter to form a roux, then thinning out that starch-fat paste with milk until the mixture turns silky smooth.

When you stir aged cheese into the sauce, starches from the flour wrap around proteins in the cheese, preventing them from squeezing out fat and recombining into slumpy curds. Some cooks even fortify the sauce with egg yolk, which adds emulsifiers that also help stabilize the emulsion.

This method is very effective. But it’s also quite fussy. Luckily, my colleague Andrea Geary developed a much simpler alternative for her Simple Stovetop Macaroni and Cheese—simply stir some American cheese into the mix.

To understand American cheese and its impact in mac and cheese, it’s helpful to start with a little history lesson. In 1903, a man named James L. Kraft moved from Canada to Chicago with $65, bought a horse and wagon, and started wholesaling cheese.

But he quickly noticed a problem. Cheese is perishable, and so there was a lot of waste and spoilage in the business of commercial cheese. He put some serious R&D into techniques for pasteurizing cheese to make something with a longer shelf life.

Right around this time, a couple of Swiss chemists, Walter Gerber and Fritz Stettler, were after the same goal. 

They both realized that simply heating cheese to pasteurization temperatures absolutely destroyed its texture. Kraft played with heating under agitation and got some pretty good results, but it was the Swiss chemists who cracked the code.

While experimenting with blending Swiss cheese and a substance called sodium citrate, they found the resulting cheese mixture melted beautifully, solidified upon cooling, and then remarkably was able to be remelted and turn out just as smooth.

They had created the first processed cheese.

As the Swiss discovered, sodium citrate, which is known as an emulsifying salt, helps cheese melt smoothly.

American cheese is made with an emulsifying salt—so when it melts, it flows.

In an aged cheese such as sharp cheddar, proteins are bonded tightly to each other with the help of calcium ions.

When you apply heat the fat melts and escapes long before that rigid protein structure softens enough to flow.

Bring sodium citrate into the equation, though, and you could get that sharp cheddar to melt smoothly without a lump in sight—and that’s exactly what happens in Andrea’s stovetop mac and cheese.

In addition to being delightfully creamy, Andrea’s mac and cheese comes together in just 20 minutes in one pot:

1. First, simmer the macaroni in a combination of water and milk, which will form the base for the sauce.
2. Then, stir in shredded American cheese (you can buy a block at the deli counter). Here’s the simple reason why: It’s got the emulsifying salts we’re after built right in.
3. After you stir the mixture until smooth and move it off the heat, add shredded extra-sharp cheddar. The emulsifying salts (and gentle heat) keep the cheddar from breaking. There you have it: The complex, aged flavor of cheddar married with the creamy texture of American.

Want to learn more cheese science? Check out this episode of What’s Eating Dan?.