How to Use Frozen Bones for Bone Broth?

Question

I've watched lots of videos on how to prepare bone broths. However, I haven't found much information about making it directly from frozen bones.

I have understood that I should move frozen bones from the freezer to the fridge at least 1 day or 2 days before to be safe. (If I want to use them normal way)

Or that I should put those frozen bones in cold water for at least 1 hour before use.

But if I want to use them directly from frozen? Can I? (without roasting them, directly just like that)

If I use a Pressure Cooker, on Low or High Pressure, I don't think there is any problem.

But if I want to use a Slow Cooker?

Generally, for frozen meat, they advice to set on High (Slow Cooker) for 1 hour and then move to Low.

But is it safe to do the same with frozen bones? From a bacterial point of view? Or should I boil them in a stove pot before (for how long?) and then transfer them to the Slow Cooker?

Maybe I'm overthinking it too much but I prefer to understand the process if possible.

Thanks for your help.

Answer 1

The key concept is the food safety 'danger zone'. There is no reason to treat bones (which will have traces of meat on them) differently to meat.

Whatever temperature they start at, you want to avoid the bones spending too much time in the danger zone temperatures. Starting from fridge temperatures rather than freezer temperatures helps this because your stove or cooker will be able to bring them to a cooking temperature faster.

As long as the quantity of bones isn't huge, starting from frozen in a pressure cooker or on a stovetop should have no problem getting to a cooking temperature quickly, but a slow cooker on its low setting might be an issue, as you have noted – follow the advice for frozen meat of using the high setting initially.

Answer 2

I use frozen bones from my butcher.

I put them frozen in the oven at high heat (with onions and other vegetables).

I will let them roast from frozen until nice color and put them in pot with water, boil and reduce temp to a simmer.

You could put them in the pot frozen and start your broth the same way you'd do with unfrozen bones.

Answer 3

There shouldn't be any problems in using frozen bones to make stock without thawing in a pressure cooker or regular cooking, you'd just crank up the heat until the bones are thawed, there's no safety concerns with that approach.

If you are going to put them in a slow cooker unattended from frozen the bones could go bad before they heat up enough for safety. However, you probably could deal with that by pouring boiling water on them instead of room temperature to get the process started. It's probably easier to just let them thaw out overnight in the fridge though. If you are around then setting it to high until the water heats up to a safe temperature will be fine. I wouldn't do 1 hour on high and then turn to low, measure the water temperature and keep it on high until it warms up enough.