Hi!
A broth is a very popular soup in Poland. There is an opinion here that it should be cooked at a low temperature to be especially rich and flavorfull. One famous polish chef even says it should be kept below 40C and shouldn't be salted, and then the osmosis takes place and all the salts, aromas and flavorfull components go into our broth. In chef Jacob's stock episode of SCS he didn't mention that such a low temp may help to do the job. I think that what makes a broth meaty, rich and tasty are the meat juices escaping from the meat, and the higher the temp the more of the juices leak from the meat. Of course the meat juices are not necessary to get the flavour, and the example is a roasted bones stock. Bones and connective tissue are crucial here as the colagen melts giving our stock its body and flavor. As I remember 40C is not enough to melt the colagen, so it looks like that polish chef is not right. My question is: If at a temperature of 40C neither meat juices nor the colagen escape the meat, then are the salts, and whatever else ( some flavorfull compounds) migrating from meat and bones thanks to osmosis, enough to make a tasty broth? I doubt, but I may be wrong. Imagine the meat after 12 hours of such a bath: full of its juices, actually raw but totally bland and tasteless, weird. If you cook it then it leaks pure water, haha. I know I have an odd sense of humor. Cheers