On the topic of raw bone broths, I've been experimenting for the past year with making bone broth using fermentation. Basically I start as if I'm making some sort of fermented beverage, kvass-style. I use half-gallon mason jars, cut or grate 1-2 cups of nutrient-dense, starchy vegetable - beets, carrots, burdock root or some other root, or red cabbage - and put it in the jar. Next add a decently sized chunk of bone, ideally with connective tissue, fat and even some shreds of meat left on. Fill the jar with water, add a few pinches of unrefined sea salt (perhaps 1/4 teaspoon) and swish the mixture to mix everything nicely. Then let it sit at room temperature for a week or two, or three.
The vegetables will start fermenting, releasing lactic acid along with all sorts of other beneficial things. The acid will help to draw alkaline minerals like calcium and magnesium out of the bone, and bacteria will start eating the physical components of the bone, liberating them into the solution as parts of the bacteria floating about. When the fermentation has used up most of the sugars in the vegetables, the broth is ready to drink (if you let it continue fermenting, other bacteria will start turning the lactic acid into acetic acid, aka vinegar).
I've noticed that when I do this, much of the fat melts off the bones and forms droplets on top of the liquid, much like when you make cooked broth. I've also noticed that most of the soft tissue on the bones is either gone or very mushy by the time the bone is removed, suggesting some serious bacterial activity there. I've finally noticed that the bone is noticeably more porous at the end than when I put it in, suggesting some of the proteins that make it up were eaten by bacteria or dissolved by the acid and entered the solution. At any rate, this seems like a workable way to make bone broth without heat.
