Learning how to churn butter can be a satisfying experience that you can do from home with a few basic tools. Churning refers to the process of agitating cream, which destabilizes the fat globules. At first, the fat globules trap air bubbles, forming whipped cream. Eventually, though, the fat begins to clump together and form butter.
The earliest churns were simple skin bags. Asian nomads would keep cream in these bags and shake them until butter formed. This concept developed into churns made from bags on rockers, which could be churned by either animals or humans.
When you think of a butter churn today, you probably picture a dash churn: a tall, wooden barrel covered with a lid with a hole in the middle, through which you could work a plunger up and down to agitate the cream. This was a very basic churn which farmers and their families used for centuries. A more modern approach, however, became popular in the 19th century: butter churns operated by turning a crank.
Technological advances in the late 19th century led to butter factories. Today, these factories use continuous churns, which can produce a ton of butter an hour. Churning your own butter will let you experience the flavor of fresh-made butter, just like people had before the 20th century. Even better, you can make butter without any specialized knowledge or tools.
First, decide whether you'd prefer sweet cream butter or the slightly sour butter generally sold in the states as "European-style." The acidic flavor comes from the traditional way of making butter: leaving milk at room temperature and gradually skimming off the cream as it rises to the top and begins to sour. If you decide to make European-style butter, combine the heavy cream and cultured buttermilk and let it sit at room temperature for 12 hours before you begin churning.
Pasteurization will also affect the flavor of your butter. Pasteurization involves heating milk to kill bacteria; this lends a slightly cooked flavor to the butter. Raw (unpasteurized) cream is preferable for churning your own butter. Be aware, however, that raw milk and other unpasteurized products can harbor bacteria, making them unsafe for children, pregnant women, the elderly and people with compromised immune systems.
Pour the cream into the blender or the bowl of the standing mixer. Blend or whisk at a low speed, then increase the speed to medium or high when the cream starts to thicken. The cream will gradually form stiff peaks, making whipped cream. As you continue to churn it, it will begin to break down into curds of butter and liquid buttermilk. At this point, slow down the standing mixer to prevent splashes. The entire churning process should take about 5 minutes in a blender or 9 minutes in a standing mixer.
Place a sieve over a mixing bowl and pour in the butter. Let the buttermilk drain away. You can use the buttermilk when recipes call for buttermilk, if you made sour butter, or in place of whole milk if you made sweet butter.
Blend the butter with ice water for 30 seconds, or knead the butter by hand with cold water, draining and adding more water until it runs clear. This will rinse the buttermilk out of the butter; otherwise the butter will go rancid. If you like, add 1/2 teaspoon butter to help preserve it and add flavor.
Wrap the butter in plastic wrap or store it in an airtight container. It will keep in your refrigerator for about a week.
(Makes about 7 ounces butter and 7 ounces buttermilk.)