How butter is made

Butter is cream that has been abused until the fat globules break their skins and clump together.

stations: 7
things upstream: 5
raw sources: 3
steps from the ground: 2

The short version

A separator spins fresh milk into cream, which is pasteurized and cooled. Churning beats the cream until the membranes around the fat globules rupture and the fat clumps into grains. The buttermilk is drained, the grains are worked into a smooth mass, salted if wanted, and packed. Commercial butter is about 80% butterfat.

Spin cream off the milk

A centrifugal separator whirls the milk so the lighter fat rises to the middle and runs off as cream. De Laval's separator, introduced in the late 1870s, made this a factory step.

Goes in
Raw milk
Pasteurize the cream

Cream is heated to kill pathogenic bacteria, then cooled. Butter made from raw cream is very rare, and it can be dangerous.

Goes in
Cream
Ripen or cool it

For cultured butter, bacteria are added and left to sour the cream. Sweet cream butter skips the culturing, and can be made in about 6 hours, compared with up to 72 hours for cultured butter.
Churn until the fat breaks out

A large drum or continuous churn agitates the cream. Churning tears the phospholipid membranes around the fat globules, and the freed fat clumps into small grains that float in a watery liquid.
Drain the buttermilk

The watery liquid is drained away and the grains may be rinsed with water. The liquid is the original buttermilk.
Work and salt the grains

Rollers or paddles press the grains into one smooth mass and squeeze out extra water. Salt, added since ancient times to help butter keep, is mixed in at this point.

Goes in
Table salt
Print and wrap

Butter is pressed into blocks, cut into sticks or tubs, and wrapped in foil or parchment.

End of the lineButter Next it goes into croissant, caramel, toffee.

Worth repeating

Commercial butter is about 80% butterfat and 15% water, and traditionally made butter can be as low as 65% fat.
Butter is almost pure milk fat, so it holds only traces of lactose.