Published: May 8, 2013
Imagine your favorite cheese: perhaps an aged, sharp cheddar, or maybe a blue Gorgonzola or a gentle Monterey Jack. Wouldn't it be wonderful to use those really good cheeses you love on nachos or as a sauce on macaroni or vegetables?
But if you've tried melting high-quality cheeses, you've experienced the problem: the cheese separates into a greasy oil slick.
One workaround is to make a Mornay sauce, which combines cheese with a cooked mixture of flour, butter and milk. But a Mornay sauce can end up tasting as much of flour as it does of cheese.
A clever Canadian-born cheesemaker discovered a much better solution around 1912. His name might ring a bell - James L. Kraft.
Kraft found that adding a small amount of sodium phosphate to the cheese as it melted kept it from turning into a mess of cheese solids swimming in a pool of oil.
You can apply the same chemistry, however, to achieve much higher culinary purposes. In place of sodium phosphate, we use sodium citrate, which is easier to find in grocery stores. Like sodium phosphate, sodium citrate is an emulsifying salt that helps tie together oil and water in cheese.
In solid form, cheese is a stable emulsion. The tiny droplets of dairy fat are suspended in water and held in place by a net of interlinked proteins. When cheese melts, however, that net breaks apart, and the oil and water tend to go their separate ways. Sodium citrate can form attachments to both fat and water molecules, so it holds everything together.
The Cooking Lab explores the delicious side of food science. It runs biweekly in Food.
MODERNIST MAC AND CHEESE
Yield: 5 servings
2 cups elbow macaroni
265 milliliters (1 1/8 cups) milk or water
11 grams (2 1/4 teaspoons) sodium citrate
285 grams (about 2 1/2 cups) finely grated white cheddar cheese Salt, to taste
Bring a large pot of water to a boil. Add the pasta and cook until al dente, 5 to 6 minutes. Drain the pasta, but do not rinse it.
Meanwhile, in a medium saucepan over medium heat, whisk together the milk or water and sodium citrate. Bring to a simmer. Add the cheese, a spoonful at a time, stirring well between additions. Continue stirring until the cheese is melted and steaming, then transfer the sauce to a food processor. Process until completely smooth, about 30 seconds.
Transfer the cheese sauce immediately back to the saucepan, and return to the heat. Once the sauce is hot, add the pasta, and stir until coated. Season with salt.
Note: You can substitute an equal amount of your favorite cheeses in this recipe. If you have an immersion blender, you can use it to blend the cheese sauce instead of transferring it to a food processor.