On Butter

Butter is a firm fat that’s made by churning (agitating) cool cream. Cream, in its unadulterated state, is an emulsion of fat within water: little butterfat globules within thin lipoprotein membranes, suspended within a watery medium. The act of churning breaks most of those membranes allowing the butterfat — a mix of different types of triglyceride molecules — to flow out.

At that point some very interesting things happen. Groups of like molecules start to collect and stack up on one another, forming crystals. The crystals collect into large masses and when the masses are pressed most of the rest of the watery medium (known as buttermilk) is expelled. The result is a reverse of the original emulsion: tiny drops of water within a medium of fat crystals, free fats and a few remaining butterfat globules.

It’s this mixture of different fats in different forms/phases that gives butter its semi-firm consistency. If butter were composed entirely of uniform fat crystals it would be hard as a rock. The structural variability gives butter a softer texture as well as “broad” melting point. That is, it melts steadily and slowly as opposed to all at once, as the various crystallized fats in the mix — which all have different melting points — go from solid to liquid. On average, butter melts at roughly 90 degrees Fahrenheit, though that can vary depending on the brand, time of year, etc..

So butter is extremely variable stuff, whose flavor, color and consistency change depending on the breed of cow, diet of the cow, location of the dairy farm and time of year.

16 thoughts on “On Butter”

  1. I’m all about the butter, but what happened with the kringle? I briefly worked in Boston and they had the best ones at the farmers’ market and I became a bit obsessed. Are you going to come back to it? It has butter…

    1. I will, I promise. I’ve just been sidetracked with requests since the year started. I have the butter I need for it!

      – Joe

  2. We moved to Ireland this year, and the butter is phenomenal…but I keep trying to figure out whether its the flour or the butter that makes all my baked goods turn out a little differently than at home. I started using “strong flour” instead of plain flour and that’s helped a lot, but could the excellent butter be making my cookies either spread or more “Cakey” than in the us?

    1. Hey Teresa!

      It could be a slightly higher fat content in the butter, but it could also be the diet of the cows. The fats in the butter might simply give it a sharper melting point so the cooking might spread faster. It also sounds like the plain flour is more akin to our soft wheat flours. Look under the “Miscellaneous Desserts and Cookies” for the chocolate chip cookie entries. There are a lot of suggestions for manipulating cookies to get the consistency you want!

      – Joe

      1. thanks Joe, I’ll check that out. Interesting about the diet of the cows and the changing the melting point of the butter, I never thought of that. All the butter here is from grass fed cows, because really we have a LOT of grass

  3. I grew up in a house where the butter was left out on the counter. Most people I know refrigerate their butter and find it strange that I don’t. It took my husband a long time before her felt sure that the butter wouldn’t be rancid after a few days, because it’s dairy and dairy should spoil. I’m certain we’ve left it out for 2 weeks with no ill effects. Why is this?

    1. Hi Jacki!

      Most of my friends’ households left butter out when I was a boy. Then when I went to live in Britain in college, everyone did as well. It’s all about what people are accustomed to.

      The reason butter doesn’t spoil easily is because it’s mostly fat, and airborne microbes don’t grow well in it. Most critters like that are geared to consuming starches and proteins. This is why fat-based preservation techniques like French confits work so well.

      A little salt also goes a long way to preserve butter, so salted butters will keep even longer. It’s my guess that people who were in the habit of keeping unsalted sweet cream butters (my family, for instance) tended to keep theirs refrigerated.

      It’s interesting…buckets of so-called “bog butter” are routinely found in the British Isles, much of it thousands of years old and essentially intact. Kept at a cool temperature (and in the case of bogs, relatively free of oxygen) fats can keep almost indefinitely.

      Thanks for the question, Jacki!

      – Joe

  4. I suspect it also depends on how hot your house is. I can keep butter out in the winter, and prefer it at that cool room temperature, but not in the summer. If you keep a warmer house than I do, it might be too warm in winter as well.

    Plus, the cat may get into it.

  5. I remember a long time ago (the 90s…) in the third grade our teacher had all the students sit in a circle and passed around four or five baby food jars filled with cream and told us to shake the living daylights out of them until “something weird happens.” It was an amazing way to teach kids how butter was made, but we were too young to appreciate the real science behind it.
    It just seems like a nice activity for a family get-together to trick the kids into making a good amount of fresh butter.

    1. Great idea, Czarina. A couple of marbles in the jar helps a lot with the agitation…of course you have to fish them out later…

      Thanks for the comment!

      – Joe

  6. The Germanic tribes (Franks, Visigoths, etc) used to put it in their hair.

    As it happens, I just came across a butter history (no doubt industry-funded) site which claims that the first instructions for butter go back 14,000 (?) years to a metal plate. Unfortunately, they don’t say which culture.

    1. Is it that webexhibits site? It’s interesting but I always seem to want more detail than they have there. Still it’s worth the time I think.

      – Joe

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