When I brought this dip to a party, explaining that it was actually made from real Pepper Jack cheese, I was met with baffled looks. "What else is in it? Butter? Cream?" my friends asked. I smiled and told them it really was just cheese, plus a little water and sodium citrate. That means there is no added fat to impair the flavor or coat your mouth when you take a bite. That pure taste of Pepper Jack cheese makes it the best queso around.
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, it will not work on proteins as sodium citrate does. Using citric acid 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.