Butter

Butter is a dairy product made from the fat and protein components of churned cream. It exists as a semi-solid emulsion at room temperature. This means it is a mixture of liquid and solid parts held together in a gel-like structure. Most butter consists of approximately 81% butterfat. People use it in many ways, such as a spread, a melted condiment, or a fat for baking and frying.

While cow's milk is the most common source, butter can be made from many mammals. This includes sheep, goats, buffalo, and yaks. The process relies on agitating the cream to separate fat globules from the buttermilk. In unhomogenized milk, tiny fat globules are surrounded by membranes made of proteins and phospholipids. These membranes act as emulsifiers to keep the fat from pooling together. Churning damages these membranes, allowing the fats to conjoin into larger masses.

The consistency of butter depends on its fat composition. It contains three forms of fat: free butterfat, butterfat crystals, and undamaged fat globules. Butters with many crystals feel harder to the touch. Commercial butter is typically about 80% butterfat and 15% water. However, traditional methods might produce butter with only 65% fat and 30% water. After churning, the small grains are often "worked" by pressing and kneading. Historically, people used wooden boards called scotch hands to consolidate the mass and remove extra buttermilk.

There are two primary types of butter: sweet cream and cultured. Sweet cream butter is made from fresh cream and is common in the United States and the United Kingdom. Cultured butter is made from cream that has fermented, allowing bacteria to convert milk sugars into lactic acid. This fermentation creates aroma compounds like diacetyl, which provide a fuller flavor. Cultured butter is preferred in much of continental Europe. In the United States, cultured butter is sometimes labeled as "European-style."

History shows that butter has played many roles in human culture. It may have been invented during the Neolithic era. Sumerian tablets from 2,500 B.C. describe the milking of cattle and identify butter as a ritual offering. Interestingly, ancient Greeks and Romans often viewed butter differently. They frequently used it as a medicine or an ointment rather than food. The Roman writer Pliny the Elder even called it a food of "barbarous nations."

In the Middle Ages, butter was often a food for peasants in Europe. Its status changed when the Roman Catholic Church allowed its consumption during Lent in the early 16th century. This led to the rise of the middle class using butter in cooking. In 2022, global production of cow milk butter reached six million tonnes. The United States led this production, accounting for 13% of the total.

Different cooking methods create specialized versions of butter. Clarified butter is made by heating butter to remove water and milk solids. This leaves almost pure butterfat. Ghee is a specific type of clarified butter heated to 120 °C. This high heat turns the milk solids brown and creates antioxidants. These antioxidants help ghee stay fresh for six to eight months.

Butter also connects to various culinary traditions and legal protections. Some regions have protected geographical indications for their specific butters. Examples include Beurre d'Isigny from France and Mantequilla de Soria from Spain. Other varieties, like whey butter, are made as a byproduct of cheese-making. Whey butter has a lower fat content and a more tangy, cheesy taste. Whether used in a Hollandaise sauce or a simple spread, butter remains a vital part of global food systems.