The Key To Smoother Cheese Sauce Might Be In Your Medicine Cabinet
If you want some classic Tex-Mex nachos, you'd better douse them in creamy, cheesy goodness. Creamy is the key word there, because nobody likes a grainy cheese sauce. You might think nacho cheese sauce is as simple as melting shredded cheese into a bit of water, but if you do that, you'll get exactly the type of texture you want to avoid. That's because cheeses typically don't liquify well.
Even the meltiest of cheeses, like mozzarella or provolone, will break apart if you try to melt them into a liquid. Cheese and water do not mix, and instead, the cheese separates into clumps of curds and a whole mess of oil. The exception to this rule is processed cheese, which won't split in a cheese sauce because it is made with emulsifying salts, typically sodium citrate.
You can make a smooth, creamy cheese sauce using processed cheese, but the trouble with most processed cheeses is that they aren't big on flavor. This is why using purely packaged cheese is cited as the common mistake that sabotages cheese sauce. Fortunately, you can achieve a sauce with the same smooth texture and not sacrifice any flavor by combining your favorite (non-processed) cheeses with a dash of sodium citrate. Finding sodium citrate at grocery stores can be hard, but if you've got a bottle of Alka-Seltzer Gold in your medicine cabinet, guess what? You already have some. Recipe developer Swetha Sivakumar from Serious Eats lighted on this genius (if unlikely) hack that renders a cheese sauce supremely smooth.
How to turn Alka-Seltzer into sodium citrate
Before going any further, it's essential to note that this method only works with aspirin-free Alka-Seltzer, which is sold as Alka-Seltzer Gold. Using Alka-Seltzer Original, which contains aspirin, could pose health risks, particularly to people who suffer from blood clotting issues. Aspirin-free Alka-Seltzer, on the other hand, should have only three active ingredients: sodium bicarbonate (baking soda), potassium bicarbonate, and anhydrous citric acid. You'll notice that sodium citrate is not one of the listed ingredients, but if you add that Alka-Seltzer to water, culinary magic will occur.
When you add Alka-Seltzer to water, it starts fizzing. What's really happening here is that carbon dioxide is being produced and is escaping from the water in bubbles, just like it does in seltzer water. When the chemical reaction is finally done, you're left with a byproduct: good old sodium citrate.
So, all you have to do to make a creamy cheese sauce is to dissolve a tablet of aspirin-free Alka-Seltzer in some water. Once the fizzing subsides, you can warm the water up using either a saucepan on the stovetop or a microwave, and gradually whisk in the shredded cheese of your choice. It should melt into a smooth, uniform sauce. You can tweak the thickness to your liking by adding more cheese or more water as needed.
Why sodium citrate makes such a great cheese sauce
Cheese contains milk fat and milk proteins, which can separate when the cheese is melted. This is especially true of aged cheeses, which is unfortunate, as those offer the most robust flavors. However, when you add sodium citrate to a cheese sauce, it binds the milk proteins and fat together, so they will not separate. It also makes the milk protein more soluble, allowing the cheese and water to emulsify into one, uniform sauce. Not only will the sauce emulsify smoothly, but it will stay that way, allowing you to make cheese sauce ahead of time and store it for later without worrying about the sauce breaking apart.
If you have neither sodium citrate nor aspirin-free Alka-Seltzer, there are other backup methods you could try, although they might have more of an impact on the flavor of your sauce. One technique is to use an acid. Citric acid will work, but you don't want your sauce to turn sour. Instead, you can make use of the tartaric acid in wine. A splash of wine is the traditional way to make a smooth fondue, and it's also the secret to Shake Shack's cheese sauce, which has just the kind of smooth consistency you want on fries, nachos, mac and cheese, etc.