the science of churning butter

As part of an annual gift exchange with my friends in honor of the Christmas holiday, I received a hand-held butter churner. Now, most people might open this gift and wonder, why would I churn my own butter when I can so easily purchase it at the store? However, my response was utter glee! I could not wait to bring the gift home and test it on some recently purchased whipping cream.

The science of whipping cream and butter is fascinating. Cream is an incredibly versatile ingredient that people consume most often in coffee or as part of making desserts. It is technically the fat-enriched portion of milk that rises to the top during the centrifuge process. According to friends who have worked in ice cream shops, over-churned cream can turn to butter. Given all these fun facts, I started to investigate the process for churning butter as part of preparing to use my new toy.

First, you must allow the cream to sit at room temperature for at least two hours. The cream will "ripen" and warm slightly out of the refrigerator. If the cream is too cold, it will not develop into butter in a timely fashion.

Second, once the cream has warmed, you pour it into the mason jar and begin to turn the handle. Within a few minutes of physical effort, the cream begins to froth. As you whip the cream, you are introducing air into the fatty liquid. In very scientific terms reminiscent of middle school chemistry, a solid network of air bubbles surrounded by fat molecules begins to form, which is what we know as whipped cream.

As you continue to churn the whipped cream, you physically damage the phospholipid membrane and cause larger portions of fat to clump together with other fatty solids. Eventually the whipped cream "breaks" and transforms into a yellow substance that looks like ricotta cheese, and then pulls together into butter! The milky liquid that separates from the solid is in fact buttermilk, which you can strain and save to make pancakes or scones.

The entire process to create butter from cream using a churning device takes about 7 minutes. In no time, you have beautifully soft and supple yellow butter that you made yourself. You can add salt, pepper, garlic, fresh herbs, or even bits of black or white truffle to flavor your butter. Spread on bread or add to some pasta and enjoy!