One of the traditional dishes we took on in Modernist Cuisine at Home is classic mac and cheese. While we have always loved this family staple, there is an inherent problem with traditional preparations: all of the virtues of using good cheese are lost when you make a cheese sauce with flour and milk, as in a traditional béchamel sauce, the standard in nearly all macaroni and cheese recipes.
Cheese is an emulsion of dairy fat and water, but that emulsion tends to break down when it gets hot. The starch particles and milk proteins in béchamel act as emulsifiers, but they aren’t very good at their job and result in poor flavor release. So, either you sacrifice the flavor of the cheese by adding far too much béchamel, or you dilute the cheese less at the cost of greasiness. We solve this problem with a little emulsion science and the use of sodium citrate.
Our modernist version of mac and cheese owes its chemistry to James L. Kraft, who in 1916 patented the first American cheese slice. He showed that sodium phosphate keeps the water and fat droplets mixed when the cheese is melted. We use sodium citrate, which has the same effect and is easier to find. The resulting texture is as smooth as melted American cheese, but as complex and intense in flavor as any of your favorite cheeses.
Tips and Substitutions
- Sodium citrate is a sodium salt of citric acid, which is found naturally in citrus fruits.
- You cannot substitute citric acid for sodium citrate in this recipe.
- Sodium citrate allows the proteins in the cheese sauce to become more soluble while lowering the pH of the sauce, which creates a smooth emulsion without curdling. Though citric acid will also lower the pH level, it will not work on proteins because sodium citrate does, and will, result in a soupy or grainy texture instead of a silky emulsion.
- Both sodium citrate and citric acid are referred to as “sour salt” and can be found in the kosher section of grocery stores. They are, however, different, so be sure to check the label in order to select the right one.
- You can also find various brands of sodium citrate online, such as WillPowder and Artistre, among others.
- Whisk the sodium citrate into the water or milk until it’s fully dissolved before bringing the mixture to a simmer.
- Add the cheese to the simmering liquid slowly, about one spoonful at a time.
- Use an immersion blender to blend each spoonful of cheese until it has become completely smooth and melted.
- If the emulsion breaks, bring the mixture to a full boil and then continue processing it with the immersion blender. The mixture should pull together. If this fails, add a spoonful of heavy cream and try again.
- Set the cheese sauce aside or refrigerate it while you cook the pasta. It will last up to one week when refrigerated, or up to two months when frozen.
- This recipe works great with a variety of cheeses, so use whatever combination you like. Some of our favorites include using Jack and Stilton and folding in roasted bell peppers and wilted baby spinach; Gorgonzola and fontina with walnuts and sautéed mushrooms; Gruyère with roasted cauliflower and roasted tomatoes; sharp cheddar and Swiss with roasted apple and crispy bacon bits; and goat Gouda and cheddar with caramelized onions and black olives. The possible combinations are endless!