Cookbook:Butter

| Basic foodstuffs | Dairy | Oil and fat

Butter is a fatty dairy product made by churning fresh cream. It is used as a condiment and for cooking in much the same ways as vegetable oils or lard.

Production
Butter is made by agitating cream, which forces the fat droplets to merge together and separate from the liquid portion. This can be done in many different ways and with a variety of tools. Historically, butter churns were used; today, mechanized churning machines make butter in large batches. If the butter is to be colored or flavored, these ingredients are added to the cream before churning; if the butter is to be cultured, a starter culture is added to sour the cream. Once the butter separates from the cream, it is washed to remove residual buttermilk, salted (if applicable), then kneaded and shaped.

To make homemade butter with simple tools, fill a jar ⅓ full with heavy cream. Shake the jar until a solid mass forms. If the cream becomes too thick to shake easily, add a bit of water. Pour off the liquid and use a spatula or spoon to collect the butter. This soft butter can be served on its own, or mixed with herbs or spices. You can also add flavor by pouring a small measure of flavored liquor in with the cream.

Composition
Butter is very high in—but not 100%—fat. North American commercial butter is typically 80–82% fat, while European butter is fattier and richer at about 82–86%. The remaining composition of butter consists of water and milk proteins in emulsion with the fat. The specific fat profile of butter gives it a lower melting point (93°F / 33°C) than other solid fats like shortening—this causes it to melt in the mouth without leaving an unpleasant coating, but this also makes it harder to create very flaky pastries with butter compared to with shortening. Butter is, though, easy to spread at room temperature, which is excellent for its use as a condiment.

Flavor
The flavor of butter depends largely on the diet of the animal that produced the cream, as well as how the cream is processed. Butter made from fresh cream (called sweet cream butter) has a very mild flavor; cultured butter, which is made from soured cream, has a more complex flavor and characteristic buttery taste of diacetyl from the microbial culture. European butter is more likely to be cultured, while North American butter is more likely to be sweet. Butter also comes either salted or unsalted—the exact salt level varies, so salted butter generally should not be used in cooking in order to allow more flexibility and adjustment.

Appearance
Butter is generally pale yellow, but it can vary from deep yellow to nearly white depending largely on what type of food the animals were eating. For example, butter is typically paler in the winter, when dairy cattle feed on stored hay rather than fresh grass. Annatto may be added to pale butter in order to give it a more golden hue.

Commercially available butter tends to be packaged in blocks; butter in the USA is commonly sold by the pound, divided into four "sticks". It can also be whipped or aerated to lighten it—this should not be used in cooking if measuring by volume.

Selection and storage
Butter is very stable and has a long shelf-life, but it will still go bad after a long period. Because the fat can eventually oxidize and turn rancid in contact with air, butter should be kept wrapped or covered. It can also go sour from bacterial contamination—you will generally be able to tell whether butter has gone bad from its flavor and aroma. It will keep well for months when wrapped and stored in the fridge or freezer. Clarified butter, which has all the water removed, will typically last even longer.

Use
Butter is widely used in cooking and baking for its flavor and texture. It can be used to fry foods, but it is not ideal for high-heat cooking, since the milk proteins it contains give it a low smoke point of about 260°F (127°C). If the flavor of butter is desired for high-heat cooking, it is best to use clarified butter, whose milk proteins have been removed. Butter is also often used as a simple condiment, and it may be spread on bread products or stirred into dishes like pasta before eating. Butter can also be used to thicken and flavor sauces and custards, such as when "mounting" a sauce by emulsifying in small pieces of the fat.

In baking, butter adds tenderness and moisture to baked goods, and the temperature and texture of the butter is often carefully controlled to affect the final texture of the product. If making a flaky or laminated pastry, it is best to use higher-fat European-style butter, which is slightly more workable and less likely to melt into the dough.

Various techniques exist to add additional flavor to butter. For example, browned butter or beurre noisette is made by gently cooking butter until its milk proteins brown, giving the final product a nutty flavor. Compound butters are simply made by incorporating flavorful ingredients such as herbs, anchovies, and sweeteners into soft butter before using or serving.