So I've made stock a couple of times in the last couple of months - one batch of chicken stock and one of beef neckbone stock - and I've come across a problem I've never seen before.

After cooling, the majority of the fat in both batches sunk to the bottom of the containers they were in. It's definitely at least mostly fat, since there was almost no fat layer to speak of on top (as there should be.)

The thought crossed my mind that it could be the storage containers, since I used regular mouth Mason jars for the beef stock, but I store my chicken stock in a big pitcher since I use it so often, and the same thing happened there.

Two different sized pots, as well: the chicken was the same 20-qt aluminum pot I always use, and the beef in a heavier stainless pot that's only 8-qt or so. Therefore, I wouldn't imagine it was the pot.

The only thing different was the butcher for the beef: our butcher where I live now is MUCH higher quality than what I used to have access to.

As a side note, while thickened, the fat did not solidify as per usual, which suggests it wasn't saturated fat (right?), but with beef...?

Does anyone have any idea what may have caused this weirdness, and how can I prevent it?

  • All lipids (fats) have a lower specific gravity than water, so they will always rise to the top. I've never, ever seen fat sink.
    – GdD
    Commented Jun 12, 2015 at 9:52
  • Neither have I - that's why I'm so damn confused. Though it didn't gel like it usually does, now that I think about it. It seemed like the bottom was thicker and the top was almost as thin as water, even though the stock was concentrated for storage. Is it possible something happened the fat and gelatin? Commented Jun 12, 2015 at 13:30
  • I thought neck was pretty lean, maybe you just didn't get much fat in the first place?
    – GdD
    Commented Jun 12, 2015 at 13:33
  • I don't usually get a lot, but I've always gotten enough to at least form that skin over the top. But I suppose its possible it was extra lean. Commented Jun 12, 2015 at 15:43
  • 2
    Did you simmer the stock or did it boil? I have heard that boiling stock will allow the fat to emulsify. (No personal experience with that, though.)
    – Cindy
    Commented Jun 12, 2015 at 18:28

3 Answers 3


Gelatin. All bones and connective have gelatin and collagen. When you cook bones slowly and gently for a long time, the gelatin leaches out in the water. Being heavier, it sinks. It isn't marrow. Marrow will stay in the beef bone until you spoon it out (lucky you). If it did fall out, it would stay in one piece. But I believe the substance you found in the bottom of your soup pot is the natural gelatin from the bones in your stock!

  • There may be fat mixed in with the gelatin. Would you recommend reheating the broth until the gelatin melts to remove the fat? If a cook wanted a clear broth should lots of bones be avoided?
    – papin
    Commented Sep 3, 2015 at 12:09
  • Fat isn't your problem. The fat would rise, as had been pointed out. The gelatin adds richness to the stock, and this comes from the bones, so you can use them. It is very very difficult to make a perfectly clear stock. To get a clear stock involves active filtering. This is an easy, standard way to clarify stock: bhg.com/recipes/how-to/cooking-basics/how-to-clarify-stock Good luck and have fun. You might consider making vegetable stock - it is healthier and easier! Good Luck
    – SusieB
    Commented Sep 4, 2015 at 13:26

Maybe it's not fat but marrow from the inside of the bones. If they were hollow after you'd cooked them, that's a sign.


If you microwave chicken skins to get most of the fat out .( I do this when I cook chicken for my dog and put the crispy skins back in the mix) you will find that a substance will form on the bottom of the container which will presumably be the natural gelatin from the connective tissue in the skins. I usually put this back in the stock.


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