I will second the sodium citrate recommendation. It should be in every kitchen if you make food with cheese that is melted. Cheap, crazy long shelf life, very easy to work with.
Adding a bit of sodium hexametaphosphate is good if you want to make cheese slices or blocks of cheese. Increases the firmness of the final product a bit and slices easier.
Adding a bit of sodium hexametaphosphate is good if you want to make cheese slices or blocks of cheese. Increases the firmness of the final product a bit and slices easier.