The Secret Ingredient For Perfectly Melted Cheese Sauce

Though it would be great if you could toss any block of cheese into a pan and watch it melt into the perfect sauce, unfortunately that's not how it works. As much as cheeses vary in taste, they also vary in properties like hardness, dryness, and creaminess. That means melting it doesn't always go smoothly, and usually requires other ingredients aside from cheese.

When making mac and cheese from scratch, for example, it's customary to start with a roux of butter and flour, and build the sauce gradually by adding shredded cheese and stirring until it comes together. The same applies to queso, in which evaporated milk and cornstarch are added along with the cheese in order to get the ideal consistency. 

But even with the right recipe, sometimes you still end up with a clumpy sauce, a result of the fat naturally separating from the cheese, Kitchn explains. This, however, is far less likely to happen with the addition of one ingredient.

It's possible to make cheese sauce without it, but most recipes call for at least some American cheese. According to Bon Appétit, this is due to the fact that it's highly meltable. At the point where other cheeses separate and turn grainy, American cheese remains creamy. The reason this happens, according to Cooks Illustrated, is that it contains sodium citrate. Sodium citrate is an emulsifying salt, and it works in American cheese by keeping the fat contained within its protein structure, per The Cheese Professor.

To make any cheese as melty as American cheese, therefore, all you need to do is add sodium citrate. Per Food & Wine, you simply shred the cheese you want to use, heat an equal amount of water, and whisk in the sodium citrate. A ratio of 1 cup of water to 1 teaspoon of sodium citrate works best, but you can easily customize it to your desired consistency, the publication states, noting that less water will yield a thicker cheese sauce. 

Once the sodium citrate is dissolved, you can add the cheese, and when it fully melts down, you'll end up with the creamiest possible cheese sauce.