Alton is not alone in the practice of using sweet (unsalted) butter and salt...this is actually a standard practice, especially in baking.

Salt is added to butter as a flavor enhancer and as a preservative so it will have a longer shelf life. Salted butter can last two to three months longer in the refrigerator than unsalted butter. So this actually means that salted butter is often much less fresh than unsalted, and sometimes has been made from cream that is less fresh as well. Also, salt can sometimes overpower the sweet flavor of the butter and can also mask odors. Additionally, the amount of salt added to salted butter varies from manufacturer to manufacturer, so it's hard to know how much extra salt you're adding to a recipe. Using unsalted butter allows the baker to control the amount of salt in a recipe and gives more consistent results. Also, unsalted butter has a fresher, more delicious flavor.

If you have no choice but to use salted butter in a recipe, you can generally replace the unsalted butter with salted butter measure for measure (they both contain the same amount of butter fat). If you do, then you will need to reduce the salt in the overall recipe. The rule of thumb is to omit about 1/4 teaspoon salt per 1/2 cup (1-stick) of butter. For some recipes, this may not matter. For others, like classic puff pastry, you may find it too salty if you don't. Salted butter may taste better on toast, but it can very easily ruin a batch of cookies or a cake.

Usually an author will specify if unsalted butter is important for the success of a recipe and you should be guided by that recommendation. If the recipe only states butter then you can usually assume that it is regular butter...however, in baking, standard practice is that unsalted butter is used most often and therefore assumed to be what is required. Also, it is preferable that foods be under- rather than over-salted. So, if you have to err, better to use unsalted butter and end up with food that is a little bland.

For clarity, I believe recipes should be explicit in stating whether the butter used is salted or unsalted. However, in the real world, that is not always the case. Also, some cookbooks give a blanket statement somewhere regarding this. My copy of "The Joy of Cooking" says, "Most of the recipes in this book call for sweet butter — first-grade butter made from sweet cream with no added salt." Since most of us don't read every word of a cookbook, we may not see a note like that. So, it's a good idea to see if there is a general section about measurements, or notes on specific ingredients, that might help. But more importantly...even if you read that blanket statement, what does "Most of the recipes in this book call for sweet butter" mean? How does specifying "most" help with anything? That's why I believe recipes should be explicit in ingredients and instructions whenever possible.

Regards,
Steve Grishka

[edited June-30-2008]

[edited June-30-2008]