Fat content in homemade stock

Question

First of all, I don't know the difference between stock, broth and bouillon in english (not my native language), but what I mean is when you cook for example a chicken carcass with vegetables for a couple of hours to use the liquid, discarding everything else. My question also applies for when you cook any other type of meat which haven't been pre-cook, meaning it will have quite a lot of fat remaining.

However, when you make your own stock, how much fat will there be in it? I'm mostly interested in the fat content after you've removed the "lid of fat" after refrigeration, but also immediately after sieving, if anyone has answer to both questions.

And naturally, I know it's hard to determine the fat content without doing an analysis, but I'm not calling for an exact answer on the gram, just if it's around 0–5 %, 5–10 %, or 10–20 % or whatever – just be as precise as you can.

When buying stock in the store, it usually says 0 g fat, but I guess they have some method of removing all of the fat, lowering the risk of it going rancid and increasing shelf-life. In my stock, I can see quite a lot of droplets of fat.

One way of attacking the question can be: Doesn't all the fat have to come up the surface ("the lid") since fat and water are unmixable? If fat is still in the broth, a) has it cooled down before all of it was allowed to rise (can be difficult in gelatin rich stocks)?, or b) can a stock hold fat in an emulsion?

Answer 1

See Stock vs Broth - What's the difference in usage?

Like most cooking words there is no global definition. Fat content varies by ingredients and recipe. Some fat is retained in suspension, and some will be chemically attracted to components of the stock and be difficult to remove

Some people stir in the fat, most people skim it off

Commercial stock may have been centrifuged to get the fat content down to zero. This is not that practical to do at home, but can be done

Answer 2

After you have completed cooking your stock and have filtered out all of the solids and let it rest in your refrigerator with a piece of cheesecloth laid across the top overnight (or for several hours...) the oils will rise to the top and solidify. After that you can (carefully) remove the cheesecloth and it will take all (or nearly all) of the oil/fat with it. You should be able to skim of the remaining solid easily enough.

After you have done this, raise the temperature of the broth back to boiling briefly and move it into mason jars (while hot) for storage. At this point, if you are looking for 'long term' storage, you need to do a pressure seal (pressure canned, as derobert mentions), if you don't expect it to last beyond 6-8 weeks then cold storage is probably good enough. If you are going to cold store it, let it cool on the counter to room temperature then move it to the fridge.