Believe it or not, the perfect secret ingredient in melty, gooey cheese sauce is Alka-Seltzer. When you know how to use it, you can make cheese sauce out of any kind of cheese that will melt, instead of reaching for the Velveeta once again. This is because Alka-Seltzer is a simple mixture of baking soda and citric acid, which combine to form sodium citrate, the emulsifying salt that makes cheese mix with water and butter, resulting in processed cheese sauce.
When you emulsify your cheese yourself, you can make a pourable sauce out of cheddar, Gruyere, Swiss, provolone, or Monterey Jack cheese, even the pre-shredded kinds that come with starch added. The method will not work with soft cheese like brie, or with aged cheese like Parmesan, and the recipe warns not to use Alka-Seltzer with aspirin. Once your cheese is made into sauce, you can add spices and peppers if you like. Read the science behind this genius method for making your own homemade cheese sauce, and the recipe that will get it done at Serious Eats. You'll be ready for customized fondue, nachos, or even mac and cheese!
(Image credit: Amanda Suarez for Serious Eats)