I normally use the bones only once, and give the beef bones to a coworker for his dog.
However, it occurred to me: I'm only pressure cooking them for an hour, so there's probably lots of goodness left.
Question: how much goodness: how many times can I use/re-freeze/reuse the bones?
I've done it with a mix of old and new beef bones, but found the flavor was not as robust. I tried it twice and the second batch (third batch of broth for half of the bones) tasted off. I'm not sure how to describe it other than thin. I used the same method all of the times, with the same herbs and aromatics.
I did notice that the marrow bones were hollow after the first go around, so I don't know if they even contributed anything to the second and third batches. Perhaps knuckle bones would be a better choice for reuse than marrow bones, but I haven't tried it.
I usually use them twice with the pressure cooker. Not sure if doing that even has any benefits, but when I am cooking them the second time around I try to use less water or cook them longer until I get the maximum amount of gelatin possible. No idea if this is beneficial, but, it probably isn't going to be harmful..
Didn't get the same quality with beef bones, but now when I use chicken feet - I get 2 amazing broths batches! But here is the problem: I can hardly stop myself from eating the feet when I am straining the first batch - anyone else love the taste?
A questions for all of you slow-cooker/pressure cooker owners: do you use vinegar in your broths? if yo do, are you not worried that the acidic vinegar will react with the surface of the device and extract unwanted lead/aluminum and such into the broth???