How is butter made?

On a microscopic level, butter is fascinating stuff. It’s been called an “inside out” emulsion since it starts out as dispersion of fat globules in a continuous phase of water (cream) and ends up as a dispersion of water droplets in a continuous phase of fat (butter). Pretty funny, eh?

I said pretty funny, eh???

(Sound of crickets chirping.)

Ehem. So how does this miracle happen? Well it all starts with preparing the cream. The first thing that happens is it’s pasteurized, i.e. heated to 185 or so degrees Fahrenheit. After that the cream is slowly cooled to about 40, at which point something very interesting happens: fat crystals start to form in the mixture. This is an important step for the ultimate texture of the butter, which depends on a careful balance of fat crystals and “free” liquid fat. Too many crystals and the butter will be brittle, too few and the butter will leak liquid fat and be overly soft and “greasy.”

Next step, the churning, whereby the mixture of fat crystals, fat globules and water is agitated. Though it seems simple enough, the process is actually quite complicated, so much so that it’s still not completely understood. Essentially what happens is this: brittle fat crystals puncture the membranes of the fat globules, which spill out their “free” fat molecules into the mixture. That free fat flows together and around the crystals forming a continuous mass. At the same time much of the water is pushed out (this water, which contains a small amount of fat plus other flotsam, notably the membranes of the fat globules, is known as buttermilk).

The final step is “working” where the butter is essentially kneaded to squeeze out any last pockets of buttermilk and bring it to an even consistency. Once that’s done it’s ready to packaged and sold. Cool, yes? Yes???

8 thoughts on “How is butter made?”

  1. Definitely cool. Especially if I could use that process to make better butter at home.

    Do you think that heating cream, then cooling it to 40 Farenheit, then whipping it with a mixer/whisk (presumably in an ice bath to keep it cool) would make better homemade butter?

    1. You know that’s an excellent, excellent point. I’ve made butter at home but would never have thought to try to imitate that process at home. I wonder if it would come out any differently. Of course commercial cream is pre-Pasteurized,would that make a difference? I can’t say I’m sure. Hmm…thanks for a very thought-provoking comment, Mari!

  2. Yes Joe Yes!!! Veeeery Cool! And… it answers the another question “Where does buttermilk really come from?” So, Thank You!

    1. Thanks Eva! There’s plenty more on all of this amidst the dairy tutorials, just in case you’re curious! – Joe

  3. The process that we follow at home everyday is some what similar. We heat the milk till it boils and then let it cool down completely (approx 4-6 hours). Then we remove the thickened cream layer and store it separately. We add a little bit of yogurt to this thickened cream and the whole cream turns into heavy yogurt. Churning this gives excellent butter and quite thick buttermilk which I usually use for cakes.

    1. Very interesting, Vrushali. It reminds me of how “clotted cream” is made in Devonshire. Thank you for the email! – Joe

  4. First – a confession, I stupidly froze four quarts of very, very, very good heavy cream – 40+ percent butterfat. I know someone should punish me. Now for the interesting observation. When I took the cream out of the freezer and defrosted it all the butter fat had congealed into lumps suspended in whey, almost the halfway point to butter. I tried heated the cream to melt the fat and then whipping it to remake the emulsion, which of course failed. I wonder if I had simply put the wrecked cream in the old KA mixer and paddled the heck out of it, if it would have made some great butter?

    1. That’s an interesting question. I’m not sure if it would have worked or not, but my feeling is that it would have. Not to rub it in or anything…

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