A frozen egg

This happened in my friend's henhouse this morning.

My friend Kate Hastings, who took this photo, thinks this egg froze because the hen cracked it slightly. But it also looks like the kind of expansion cracking that you can get when eggs freeze and burst their own shells. When the water in the egg white and yolk freezes, it forms a crystalline structure — and that structure isn't very tightly packed. There's lots of space between the molecules, which means that solid ice takes up more space than the liquid it replaced. If the egg freezes solid enough, it's got nowhere left to expand except outside the shell.

Eggshells, as it turns out, are not a great insulator from the cold. Chicken butts are, but chickens also don't always sit on their eggs consistently enough to keep those eggs from freezing.

One side note: You can actually thaw and eat frozen eggs. But you shouldn't thaw and eat an egg like this. That's because the shell is actually a pretty good barrier against bacteria. If a fresh egg — the kind sitting under a hen — has cracked, there's a higher likelihood of bacterial infiltration.

Thanks to Kate and Grampaw!


  1. This blog repeatedly posts stuff that makes me snicker.

    A frozen egg! OMG!!  That’s the sort of thing you’d only see … in the winter time, I guess.

    One of my favorites was when somebody posted a craigslist add for fainting goats with a sort of surprised and bemused update with a link to the myotonic goats wiki like they were some exotic secret.

  2. So I collected eggs this morning at my coop in 3 degree weather, and I’m assuming that if doesn’t crack, it’s not frozen yet? Do they sometimes freeze without cracking?

    1. I had the refrigerator turned up too high and had a partially frozen egg with an intact shell. It was like the yolk was suspended in an albumen slushy.

    2. I had four frozen eggs yesterday morning (out of five).  Only one was cracked; the other three were like a thick sugary syrup, but ice crystals instead.

      Long time, no see.  Funny running into someone I know on BoingBoing comment threads.

    3. In my experience if the egg is completely frozen it will crack but if its only partially frozen it may survive. The other day I brought in our eggs and some of them cracked when I set them down and other didn’t. I made an omlet and all of the eggs had semi-frozen portions that had to thaw in the pan.

      PS. I always wash my egg shells before cooking.

  3. A friend of mine had Leghorn chickens, which have been bred to not sit/guard their eggs much. She had to check regularly in the winter, or run the risk of wasting a lot of eggs. 

  4. If I get frozen ones that don’t crack, I thaw and eat them. Ones that do crack I thaw and cook and feed back to the chickens. It seems so wrong, but they dig it, and it’s nutritious! (Scramble them so they don’t make the connection that the things that fall out their butts every day is food).

  5. Frozen eggs have a terrible texture if cooked as an egg; boiled, fried, scrambled etc.. They’re suitable for baking though. 

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