butter [buht-er] noun
A solid dairy fat to use in dessert making, made from many different dairy sources (sheep, goat, yak) – but we are primarily concerned with butter made from cow’s milk and cream. This is a churned product that begins with sweet milk/cream or milk/cream that is slightly cultured. In the U.S., the butterfat content must be at least 80%, with most coming in between 80% and 82%.
The Bakepedia test kitchen uses Land O’ Lakes for testing our recipes. There are high-fat versions available (such as Plugra) that contain as much as 86% butterfat. If you use a high-fat butter in a recipe that was developed with a lower, standard-fat variety, the recipe might not work. The rest of butter’s composition is made up of water, milk fat and sometimes salt, which is added to commercial products as a preservative; it also alters the flavor.
Most baking recipes recommend sweet (that is, uncultured) unsalted butter, but always use what is called for. If the recipe just says “butter,” assume unsalted. Do not substitute whipped for regular in recipes. It has air whipped in and will greatly affect the recipe ratios. Margarine, which is a hydrogenated oil product, is used as a substitution for butter by many bakers. In our opinion, it is not an even trade, neither in nutrition nor in reference to texture or flavor. Results will vary greatly.