Weird Science: Shaking Cream

HONOLULU (HawaiiNewsNow)-This is a great and really easy experiment to show you keiki the structure of milk! Check out the video!

Dr. V Show:  Making butter

Things you will need:

  • Heavy cream
  • Jar with a lid
  • Cling wrap

The Experiment:

Put some heavy cream in your jar and cover it with the cling wrap, then the lid. The cling wrap will help keep it from leaking. Make sure your lid is on tight and then start shaking! Shake your jar for about 10 minutes, but stop every so often and roll it around to see the consistency of the milk. At one point, it should look very thick and lumpy. Shake it just a while longer and what does your heavy cream look like?

How does it work?

Cream is basically made up of water filled with 36-40% fat globules (globs). These globules are very small and are mixed throughout the cream in a stable solution knows as a colloid. These globules tend to repel one another, so they stay about the same size and flow past each other very easily, as you could tell from pouring the cream into your jar. Shaking the jar can overcome the repulsion between the globules and cause them to start joining up. These larger globules don't flow past each other as easily, so the mixture gets thicker. Eventually, the cream separates into mostly fat, which is butter, and mostly water, which is known as buttermilk. Because the fat is airtight, oxygen can't get into the butter, so bacteria cannot grow very well. This means that butter will last much long than milk or cream, which is why butter was churned in the first place. You've just made your own butter!