Forum: cooking.stackexchange.com
Tags: <meat><stock><bones>
Title: How can I increase the extraction of gelatin and minerals from bones into my stock?
Question: I am interested in knowing how I can increase the solubility of gelatin, marrow, and minerals in my stock.  Thanks.

Answers:
sents: text: In terms of commercial food processing, there are more efficient ways to extract gelatin than slow-simmering the bones, generally by treating the organic matter with a strong acid prior to boiling, then using commercial evaporation and filtering equipment which is far more efficient than anything a home or even restaurant cook has access to.
text: According to Gelatin Food Science (see the "Gelatin Manufacture" section) it can also be first treated with a strong base solution before acidifying it, which lowers the isoionic point.
text: It's kind of difficult to explain exactly what that is if you don't have a background in organic chemistry; technically speaking it's a relationship between pH and electrical charge -
text: but applied to extraction
text: it refers to the pH at which the solubility of a protein (such as gelatin) is the lowest .
text: Lowering this is a good thing in extraction, because it means that the gelatin will be easier to filter out in an acidic solution.
text: Thus I have to point out the question is actually a bit contradictory; if your goal is the extraction of gelatin then you want to decrease the solubility.
text: But I think this is all going to be beside the point anyway, because none of this applies to stock making; the goal in food processing is to extract the pure gelatin, not to get a flavourful stock.
text: When making a stock you definitely don't want to use an acid solution, it's going to ruin the flavour.
text: Realistically, when it comes to stock-making, especially at home, the only way you're going to be able to extract more gelatin is to simmer it longer.
text: That's it.
text: When the bones break without any resistance, that means you've denatured all the collagen and you've got all the gelatin you're going to get.
text: I wouldn't worry about solubility because typically in stock-making you're already using more than enough water to dissolve all the gelatin that you could possibly hope to extract.
answer_details: author: cooking.stackexchange.com/users/41/Aaronut
score: 6
sents: text: Starting your stock with cold water and 1/4 cup of vinegar should help you get the most goodness out of your bones.
text: If you want a more gelatinous stock, try adding in extra wings/feet* for poultry, or veal knuckle bones for beef.
text: For a pork stock, pork neck bones work quite well.
text: It's also helpful to break or crack the bones to expose the marrow.
text: *
text: Chicken feet are awesome.
text: They make a very gelatinous stock, but don't impart any chickeny flavor.
text: They also look creepy.
text: If you get feet that still have skin and nails on, you can just peel the skin off like a glove.
text: The nails have layers that will pop right off.
text: That's the best way to clean them.
answer_details: author: cooking.stackexchange.com/users/3577/Mrs. Garden
score: 3
sents: text: If you have a pressure cooker, try using that.
text: You only need to cook it under pressure for about an hour, plus 20-30 minutes for it to reach pressure in the first place.
answer_details: author: cooking.stackexchange.com/users/613/Kenster
score: 2
sents: text: Long, slow simmering of the meat and bones - I usually do it overnight - extracts (into the stock)
text: all of the gelatin available, but if you put the aromatic veg in at the beginning of this process, you will lose a lot of the flavor in the long cooking.
text: According to the CIA cookbook, you should put the aromatics in for the last hour.
answer_details: author: cooking.stackexchange.com/users/7994/Kimball Robinson
score: 2
sents: text: Purely anecdotal, but I find that boiling turkey bones for hours gives me as much gelatin as I can handle.
text: My stock turns into jello when I refrigerate it.
answer_details: author: cooking.stackexchange.com/users/2926/Mark Ransom
score: 1
sents: text: It's probably worth pointing out that "simmering for hours" for me means at least (or about) 11 or 12 for turkey, and I don't even start getting flavor out of chicken bones until 4 hours in, and that too I keep going for 12.
text: Some recipes seem to suggest that you can simmer for just 4-8, and that just doesn't work the same.
text: So, yeah, "simmer longer.
text: "
text: And if you're simmering for that long already, then I don't know.
answer_details: author: cooking.stackexchange.com/users/3712/quodlibetor
score: 0

Summary of the answers:
You can start with cold water and 1/4 cup of vinegar, then simmer slowly for about 12 hours. If you have a pressure cooker, you could use that.
Cook the stock overnight to get out all the gelatin.