Ask a Cook: Why bother to use unsalted butter and add salt?

Q: I’m confused. Recipes call for butter with no salt and then add salt. Why not skip a step and use salted butter?

A: There are two reasons that doesn't work well. First, salt is used as a preservative, so salted butter sometimes doesn't taste as fresh. Even when you're using high-quality salted butter, the formula for the amount of salt added varies. So you can't predict how salty it will taste. That can be difficult, especially in baking when it's hard to taste raw batters and doughs. It's easier to use unsalted butter and add the amount of salt called for in the recipe.