Why does churning cream make butter

Cows' milk, as well as that of most other mammals, is a complex mixture of proteins, fats, water, carbohydrates, minerals, hormones and various other molecules. Some of these components are soluble in water, others are suspended. The first step to making butter is to let cow's milk rest or centrifuge it to speed up the process until a lot of the fatty constituents have floated to the top.

We call this layer the cream , and it is skimmed off, heated up and then cooled, to harden the fats. They were shallow with a sharp edge and had perforations to catch the cream while letting the milk drip through. After the cream was skimmed, the remaining skim milk could be consumed by the family. Setting the cream aside for 24 hours at room temperature would allow the cream to sour a bit. First used was a plunge or dash churn where the up and down action of the wooden plunger or dasher a flat wooden circle or cross piece attached to the round wooden handle agitates the cream.

Another larger paddle churn is the box churn shown on the far left. Other types of churns were spun or rocked back and forth for the agitating action.

The barrel churn does not have paddles but the rotating action of the barrel produced the butter. Note the plug at the bottom for draining the buttermilk and the glass-covered peephole at the top for viewing the butter.

Pressing the finished butter into wooden molds with carved patterns gave a classy appearance to the butter served on a table. 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 what we call buttermilk. Thus, the cream separates into butter and buttermilk. Historians have found evidence suggesting that butter has existed since BC and the butter churn was created somewhere around BC. The process was quite time-consuming and demanded a lot of dedication. Fortunately, we have different kinds of butter churns today, including electric ones.

What is the science behind this? Well, it is rather straightforward as well. During the churning process, the cream gets vigorously stirred up. The agitation breaks the membranes of fat molecules, making them clump together.

As large clusters of fat collect, they begin forming a network. Also, the churning process generates bubbles of air that trap the liquid and produce the foam separating one substance from another. All this clumped fat is butter, whereas the liquid separated from it is called buttermilk.

But how about butter that is made from milk? The truth is that it is not made from milk. Whole milk has to sit until fat molecules float up and create a thick layer on the surface. The most effective way to do that is using a milk separator. There are different types of churns. Although they work pretty similarly, there are certain differences between them. A plunger butter churn is the most historically outstanding type. It often consists of a wooden barrel and a stick that has a disc with holes attached to it.

One had to pour milk or cream into the barrel and move the stick up and down inside it for a good minutes in order to produce butter. Obviously, this type of churn is no longer used. Well, at least not by the masses. Maybe there are still people out there who enjoy the process. This is another outdated butter-churning machine. It was widely used in Europe during the 18th century.

The mechanism is simple: There is a barrel that one has to fill with milk or cream.