Butter is a dairy product made from the fat and protein components of churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 80% butterfat. It is used at room temperature as a spread, melted as a condiment, and used as an ingredient in baking, sauce making, pan frying, and other cooking procedures.
Most frequently made from cow's milk, butter can also be manufactured from the milk of other mammals, including sheep, goats, buffalo, and yaks. It is made by churning milk or cream to separate the fat globules from the buttermilk. Salt and food colorings are sometimes added to butter. Rendering butter, removing the water and milk solids, produces clarified butter or ghee, which is almost entirely butterfat.
Butter is a water-in-oil emulsion resulting from an inversion of the cream, where the milk proteins are the emulsifiers. Butter remains a firm solid when refrigerated, but softens to a spreadable consistency at room temperature, and melts to a thin liquid consistency at 32 to 35 °C (90 to 95 °F). The density of butter is 911 grams per litre (0.950 lb per US pint).[1] It generally has a pale yellow color, but varies from deep yellow to nearly white. Its natural, unmodified color is dependent on the source animal's feed and genetics, but the commercial manufacturing process sometimes manipulates the color with food colorings like annatto[2] or carotene.
The word butter derives (via Germanic languages) from the Latin butyrum,[3] which is the latinisation of the Greek βούτυρον (bouturon).[4][5] This may be a compound of βοῦς (bous), "ox, cow"[6] + τυρός (turos), "cheese", that is "cow-cheese".[7][8] The word turos ("cheese") is attested in Mycenaean Greek.[9] The latinized form is found in the name butyric acid, a compound found in rancid butter[10] and dairy products such as Parmesan cheese.[11]
Unhomogenized milk and cream contain butterfat in microscopic globules. These globules are surrounded by membranes made of phospholipids (fatty acid emulsifiers) and proteins, which prevent the fat in milk from pooling together into a single mass. Butter is produced by agitating cream, which damages these membranes and allows the milk fats to conjoin, separating from the other parts of the cream. Variations in the production method will create butters with different consistencies, mostly due to the butterfat composition in the finished product. Butter contains fat in three separate forms: free butterfat, butterfat crystals, and undamaged fat globules. In the finished product, different proportions of these forms result in different consistencies within the butter; butters with many crystals are harder than butters dominated by free fats.[citation needed]
Churning produces small butter grains floating in the water-based portion of the cream. This watery liquid is called buttermilk—although the buttermilk most common today is instead a directly fermented skimmed milk.[12] The buttermilk is drained off; sometimes more buttermilk is removed by rinsing the grains with water. Then the grains are "worked": pressed and kneaded together. When prepared manually, this is done using wooden boards called scotch hands. This consolidates the butter into a solid mass and breaks up embedded pockets of buttermilk or water into tiny droplets.[citation needed]