How Does a Butter Churn Work?

Agitating the Cream

Butter churns begin their work when cool cream is added to the churn's base and a lid with a churning device (usually either a pole that feeds through the lid or a hand-crank attached to a rotating device in the churn) is placed securely on top of the churn's base. When the cream is first agitated, the motion disrupts the makeup of the milk fat. The fragile membranes surrounding the fat globules are broken down, allowing those molecules to fuse with each other and form small clumps (known as butter grains).

Fat Globules Fuse

After the grains form, they continue to fuse with other grains to form larger clumps of fat globules. As these clumps are churned, they mesh with air bubbles that are introduced into the fats by the constant motion. The clumps become more dense as more fat globules grab on and the foamy air bubbles are forced out of the network and pop. The resulting liquid is buttermilk.

Butter Separates From Buttermilk

After about 30 minutes to an hour of constant churning, the fat globules form into a solid mass of butter and completely separate from the buttermilk. Once the buttermilk is drained off, the butter is squeezed to remove any excess liquid and air and fully incorporate the globules into the smooth mass.