Warning: This technique only works with aspirin-free Alka-Seltzer, which is sold under the Alka-Seltzer Gold label. The ingredient list should only contain anhydrous citric acid, potassium bicarbonate, and sodium bicarbonate. Do not, under any circumstances, use Alka-Seltzer with aspirin in this recipe: The presence of aspirin could pose extremely serious health risks to anyone who consumes it in this cheese sauce and must be avoided.

What if I told you that there’s a way to make a cheese sauce as smooth and creamy as a jar of Velveeta from just about any melting cheese with nothing more than a single innocuous ingredient that is possibly already in your medicine cabinet. That’s right: no emulsifying salts that require a special order, no futzing with cornstarch and evaporated milk, and no floury roux. The secret ingredient is Aspirin-Free Alka-Seltzer and today is the day that I reveal its cheese-sauce-making superpower to the world. It’s been hiding in plain sight all along, each tablet formulated with a few basic ingredients that drive a chemical reaction that, yes, can treat indigestion, but—as will be clear once you understand the science—are just as good at making the elusive perfect cheese sauce for nachos and mac and cheese.

This is life-changing stuff. Ready to learn how and why?

Why a Smooth and Creamy Cheese Sauce Is So Hard to Make

Take a slice of good unprocessed melting cheese like Swiss, mozzarella, provolone, or cheddar and put it between bread slices. Grill it and the cheese melts perfectly, creating a rich, gooey, delicious treat. But when you try to make a cheese sauce by heating those same cheeses with water, you get a broken, clumpy mess instead of a glossy and smooth sauce. Why is that?

Natural cheeses don’t mix well with water when heated, instead separating into tight little cheesy clumps and pools of oil and water. This is a natural consequence of cheesemaking: To make cheese, enzymes like rennet or acids like lemon juice are added to milk, causing the proteins in the milk to coagulate into largely insoluble, calcium-rich curds that can be separated from the liquid whey and turned into cheese.

The word “insoluble” is key here—the milk proteins that have formed those curds do not want to dissolve back into water. So how can we expect them to blend smoothly with water again when it comes time to make a cheese sauce? The answer is, we can’t, not without some help to solve the problem, at least. The helper in this case is some kind of emulsifier, such as starches like flour or emulsifying salts like sodium citrate.

How Emulsifying Salts Like Sodium Citrate Make Smooth and Creamy Cheese Sauce Possible

Think of sodium citrate like a smooth operator: It has a strong affinity to calcium, and, when added to melting cheese, it can draw out calcium and swap it with sodium ions to form sodium caseinate. Sodium caseinate happens to be the most soluble form of caseinate, so once this switch happens, the protein in the cheese is able to both soak up more water and disperse well in it, trapping fat, and leading to a more stable emulsion. The more calcium the sodium citrate is able to swap, the better the emulsion works.

This is how you get that dreamy, creamy cheese sauce we all want. In fact, this is how processed cheeses like American cheese are made: Emulsifying salts are added, ensuring absolutely perfect melting no matter what.

The only problem with American cheese is it isn’t the best in the flavor department. If you want to use your favorite cheese and still get a sauce as smooth as what American cheese is capable of, you need to add the sodium citrate yourself. Of course that means making the effort to buy and stock sodium citrate in your pantry—not impossible in this day of online ordering, but it’s not exactly the kind of stuff you can pick up at your local Walmart.

Know what you can buy at your local Walmart? Aspirin-free Alka-Seltzer. Maybe you don’t even need to buy it, maybe you already have it—I wouldn’t be surprised if the ideal reader of this article is also a prime Alka-Seltzer customer…this is rich food, after all.

The Cheese-Making Magic of Alka-Seltzer, Explained

When you read the ingredients on a box of non-aspirin Alka-Seltzer, you’ll see three main ingredients: sodium bicarbonate, potassium bicarbonate, and anhydrous citric acid. You may also see some flavorings and other non-active ingredients. If you see aspirin in the ingredients, absolutely do not use the Alka-Seltzer for this culinary purpose (see warning at the top of this article).

Let’s break down what those three active ingredients are:

• Sodium bicarbonate is just baking soda by its chemical name. It’s alkaline, meaning it has a high pH, and reacts with acids to create carbon dioxide, which is why it is an effective leavening agent. We use it all the time in the kitchen, there is nothing to worry about there.
• Potassium bicarbonate is another alkaline ingredient with common culinary uses. Like sodium bicarbonate, it can be used as a chemical leavener, and it is also a common ingredient in club soda. Once again, no worries, this is safe stuff.
• Anhydrous citric acid is a form of the same kind of acid that makes lemons and limes naturally sour. “Anhydrous” just means the substance is in a dry form. The acid is an important part of the formulation of Alka-Seltzer for the same reason acids in baking necessary to make alkaline leaveners like baking soda work: They react with each other to form carbon dioxide gas.

But let’s take a closer look at the chemical reaction between citric acid and one of those alkaline ingredients, because the resulting carbon dioxide is just one of a few products, and as far as our cheesemaking interests go, it’s not the important one. When you drop an Alka-Seltzer tablet into water, here’s what happens:

3NaHCO₃ + C₆H₈O₇ —> 3CO₂ + 3H₂O + Na₃C₆H₅O₇

Sodium bicarbonate +  citric acid = carbon dioxide + water + sodium citrate

Once added to water, Alka-Seltzer quickly starts bubbling because it makes carbon dioxide gas. The cool part is, the entire reaction happens without needing any extra heat (unlike some other leaveners…cough! baking powder…cough!). 

And guess what? The salt made during this reaction is our beloved sodium citrate! See, you don’t have to hunt down sodium citrate, you can just make it via the magic of an Alka-Seltzer tablet and some water.

Using Alka-Seltzer to Make Cheese Sauce

This recipe is really easy, you don’t even need a saucepan. Just use a microwave and a microwave-safe bowl. Put an original flavored aspirin-free Alka-Seltzer tablet in water —don’t use lime or other flavors, as they’ll affect the cheese sauce taste. Let the fizz settle, which you can do ahead of time (we’re after the resulting salt, not the bubbles). If you rush and add cheese before it’s done fizzing, you’ll get foamy cheese, which isn’t as tasty as smooth sauce.

Now, add unsalted butter, which helps balance the sodium from the sodium citrate and microwave until the butter melts.

After that, add a shredded melting cheese—you know, cheeses like cheddar, Gruyere, Swiss, provolone, Jack, that kind of stuff (not soft-rind cheese like brie, and not aged cheese like Parmigiano-Reggiano). This can be cheese you shredded yourself, or a pre-shredded cheese. (Pre-shredded cheeses often have anti-caking agents like tapioca starch in them; those anti-caking starches will further enhance the creamy texture of the sauce, but the recipe works with or without them.) Microwave in 30-second intervals until the sauce is hot and bubbly. It may seem runny at first, but it’ll thicken quickly as it cools.

Finally, add any flavorings you may want, like cayenne, mustard, milk powder, jalapeños, or black pepper. After that, your sauce is ready for nachos, mac and cheese, or anything else.

And if you get a nasty case of heartburn, well, you’re in luck, because you already have the Alka-Seltzer ready and waiting.