Can salted butter be substituted for unsalted when making brown butter sauces?
While we strongly recommend using unsalted butter for baking applications, where water content and variable salt content can alter results, the answer was less clear when it came to making sauces. We always call for unsalted butter when browning so that we can control the seasoning, but perhaps browning and seasoning could be accomplished in a single maneuver. We browned 4 tablespoons of salted butter in one skillet and the same amount of unsalted butter in another. Surprisingly, the salted butter appeared to yield more than twice the volume of browned particles as the unsalted butter. It was impressive visually, but when we tasted them we found that the browned salted butter was no deeper or richer in flavor than the unsalted. (When browning butter, the milk solids develop color during cooking and provide the rich, nutty flavor.) What was happening? Salted butter, after all, is just unsalted butter with salt added; it doesn’t contain more milk solids.
So we ran a second test. We calculated how much salt is in 4 tablespoons of salted butter and incorporated that amount into an equal amount of unsalted butter. We then browned both butters, strained the results, and compared them. This time, we ended up with exactly the same volume of browned solids. It turned out that the salt was being coated in the browned milk solids, adding bulk but not any flavor.
The salted butter also foams more than unsalted butter as it melts, which makes it hard to judge the color change.
So while it’s possible to brown salted butter, there will be no browned-milk-solid flavor benefit from it and it’s actually more difficult to avoid burning salted butter compared with unsalted. The best bet is to stick with using unsalted butter.