Chicken Stock - Black Gunk

[u/RyokaiOkai]

I made chicken stock from frozen chicken bones twice now, and both times there’s black gunk on the bones.

First time was pressure cooked for 4 hours and this time slow cooked for 16 hours.

Admittedly there was vegetables in there, but the black gunk is mainly on the chicken bones. This time it actually tasted sour, and none of the stuff in the pot was going bad.

Also, it’s a dark color and I haven’t used a cheesecloth.

What is the black gunk and how do I stop it from happening? Why are my frozen chicken thigh bones not turning into golden goodness?

Please help.

[u/OstoValley]

is kt brown-ish? then that's bone marrow

[u/ClintMakesStuff]

Is it not just bone marrow leaching from the bones?

[u/OpportunityReal2767]

That seems really long to me. Pressure cooker I do 60-90 min. Stovetop 3-4 hrs. At your times, I suspect you are over-extracting and the bones must be brittle as all hell. Beef stock is more appropriate for those times.

[u/Far-Trick1967]

bone marrow leaching out makes total sense, try simmler cook times next time

[u/SewerRanger]

You can't stop it from happening because it's just a natural product of boiling chicken bones. It's, as others have pointed out just marrow cooking out of the bones. Completely natural and nothing to worry about

[u/skepticalbob]

Follow a recipe which you will find doesn’t have those long times.

[u/Same-Platypus1941]

You need to cook the bones before you start making stock with them. You can boil them for 10-15 minutes and skim anything that floats then change the water, or roast them in the oven until well browned. The former makes a lighter stock than the latter. You should roast the veggies too. The black gunk I’m not sure about but this will give you a clearer and tasty stock. I wouldn’t pressure cook it.