Fats

Classic emulsified sauces call for a large amount of fat, usually butter, added to a given number of egg yolks. In the nineteenth century, when these sauces were standardized, people were less concerned with eating fat and in fact associated rich sauces with luxury and wealth. One of the most obvious modifications of classic egg yolk sauces is simply to add less fat. The result is a sauce that contains a higher proportion of air and hence fewer calories.

Because much of the flavor of these sauces depends on the type and quality of the fat used, serious thought should be given to which type of fat to use, even if the proportion of fat is less than in a traditional sauce. When using butter, use the best quality available. Never use salted butter in sauce making; the salt interferes with the seasoning of the sauce, and salted butter has a less delicate flavor and is often less fresh than sweet butter.