Butter Buying and Storing Basics

Salted or Unsalted? In the test kitchen, we use unsalted butter almost exclusively and add our own salt to recipes. Why? First, the amount of salt in salted butter varies from brand to brand—on average 1/3 teaspoon a stick—which makes offering a universal conversion impossible. Second, salted butter almost always contains more water, which can interfere with gluten development—particularly important in baking. (Biscuits made with salted butter were noticeably mushy.) Third, salt masks butter’s naturally sweet, delicate flavors; in butter-specific recipes like beurre blanc and buttercream frosting, we found that extra salt to be overwhelming.

Plain or Premium? While you hear a lot about the higher fat content in premium butters, they actually contain only about a gram more per tablespoon than regular butter, and even our tasters had trouble telling the difference. The real distinction is culturing—the process of fermenting the cream before churning it that builds tangy, complex flavors. That said, these nuances are subtle in most cooked applications, so we save the expensive cultured stuff for spreading on toast.

Storing Placed in the back of the fridge where it’s coldest (not in the small door compartment), butter will keep for 2 ½ weeks. In tests we’ve found that any longer and it can turn rancid as its fatty acids oxidize. For longer storage (up to four months), move it to the freezer. Also, since butter quickly picks up odors and flavors, we like to slip the sticks into a zipper-lock bag.

Stick or whipped? Whipped butter, made by beating air into butter, makes a creamy spread but isn’t always a good alternative to stick butter for cooking. While testers couldn’t tell the difference in baked goods, they found the aerated butter “foamy” and “plastic-like” in uncooked applications such as frosting. If you want to use whipped butter, base your substitution on weight, not volume. (Adding air increases the volume, not the weight.) A standard tub of whipped butter weighs 8 ounces, equal to two sticks of butter.