I typically make stocks in my pressure cooker, and while they come out reasonably clear, I've heard that making stock at a lower temperature will result in a clearer stock, so I decided to try and make it in my slow cooker.
Generally, I use thigh bones, and skin, the usual veggies & herbs (garlic, onion, celery, carrots, parsley, bay leaf, and a tomato for acid), some sea salt and black peppercorns, along with some water.
I normally pressure cook it for about 1 hour 15 min, but since I was doing it in a slow cooker, I went for 7 hours. The last step is I line a fine mesh strainer with some cheesecloth then strain it into a bowl, and ladle the stock into jars to place in the fridge.
Normally the fat separates once it completely cools, and all is good. This time around, a couple hours into cooling, I noticed floating debris beginning to "clump" together in the broth. It's not necessarily rising to the top with the fat either, some appears to be sinking to the bottom. This is kind of annoying me since I strained it just like I would any other time.
What is this stuff? Are these clumps just the proteins joining together? Is it common to have to strain the broth a second time to get rid of these? I just hate wasting more cheesecloth and dirtying up bowls and strainers again to have to do this twice each time when I make stock in a slow cooker.