Churning (butter) - The Creation Process

The Creation Process

Changing whole milk to butter is a process of transforming a fat-in-water emulsion (milk) to a water-in-fat emulsion (butter). Whole milk is a dilute emulsion of tiny fat globules surrounded by lipoprotein membranes that keep the fat globules separate from one another.

Butter is made from cream that has been separated from whole milk and then cooled; fat droplets clump more easily when hard rather than soft. However, making good butter also depends upon other factors, such as the fat content of the cream and its acidity.

The process can be summarized in 3 steps:

1. Churning physically agitates the cream until it ruptures the fragile membranes surrounding the milk fat. Once broken, the fat droplets can join with each other and form clumps of fat, or butter grains.
2. As churning continues, larger clusters of fat collect until they begin to form a network with the air bubbles that are generated by the churning; this traps the liquid and produces a foam. As the fat clumps increase in size, there are also fewer to enclose the air cells. So the bubbles pop, run together, and the foam begins to leak. This leakage is called buttermilk.
3. The cream separates into butter and buttermilk. The buttermilk is drained off, and the remaining butter is kneaded to form a network of fat crystals that becomes the continuous phase, or dispersion medium, of a water-in-fat emulsion. Working the butter also creates its desired smoothness. Eventually the water droplets become so finely dispersed in the fat that butter’s texture seems dry. Then it is frozen into cubes, then melted, then frozen again into bigger chunks to sell.