Making Beef Stock

Stock is one of those generally useful things for cooking - it's used as a base for soup and sauces, you can use it to cook things in, etc.  This post is about making rich brown beef stock using roasted bones and mirepoix (onions, carrots, celery).  The process is pretty simple, albeit time consuming - you start by roasting the bones and the vegetables, then put them in a pot with water, heat the water up to a slow simmer, and let it sit and extract all the goodness.  After a while (a day), you strain everything out, add a new batch of mirepoix to the bones, add more water, and do a second extraction (called remoulage in culinary terms).

I started by getting bones at the supermarket. At Gelson's they charge $1.50 a pound for beef knuckles, which are actually more like the ends of the femur or humerus. The middle of those long bones gets sold for a lot more as marrow bones.   If you ask, the butcher will saw the knuckles up into chunks, which is good - you want to expose the marrow in the interior of the bone, since that's one of the primary sources of flavor.

 The traditional vegetables for making stock are onions, celery, and carrots in a roughly 2:1:1 ratio, although it's hardly critical. For this particular batch, I had a bunch of mushrooms getting slimy in the refrigerator, so I cut those up and added them to the roasting pan.  This is also when I go rummaging for scraps of meat from trimming a roast or other piece of meat to size.  If you have that chunk of frozen hamburger meat you forgot about and is all freezer burned and ugly, this is the time to use it.

I shoved the pan in the oven at 375-400 degrees for a few hours until it was nice and brown.  A couple times during the roasting process, I turned the bones and vegetables over.  I've also put the bones on a half sheet pan in a single layer, and that works a bit better - the roasting pan holds more of the moisture in, and you actually want the stuff to lose some of the water, and cook in the rendered out fat.

Roasting is the key to flavor - it's that Maillard reaction converting proteins and starches into sugar.  Roasting also helps render out some of the fat.  I guess, in theory, one could save the fat for cooking something, but it has a pretty strong flavor when you're doing beef (when you make chicken stock, the fat is much more pleasant flavored, and is called schmaltz in traditional German cooking).  If you're making french fries, beef fat is apparently what you want for optimum flavor - really high smoke point, good taste.  To be honest, though, I like frying potatoes in duck fat.

The next step is to prepare the stock pot - if you aren't roasting your vegetables separately, then it all goes in together.  If you're roasting separately, or not roasting the vegetables at all, throw them in the bottom. A handful of parsley, and all those bones on the top.  Cover it all with water - in theory, cold water and heating slowly is supposed to make the stock more clear, but I wind up filtering it anyway, so I've not worried about it.  You need a BIG pot - I use the pot from my pressure cooker - it's big, sturdy, and works ok.
 This is the pot being prepared for the second extraction, but it's the same general idea the first time. There's no special exotic skill required here.

Then turn on the heat and wait, and wait, and wait.  It will warm up, and you'll start to see scum form on the surface as well as fat accumulating.  Skim those off periodically with a ladle.  The scum is from denatured proteins and it also traps other particulates. You don't want a rolling boil, just a gentle simmer.  What I do is put the pot to one side of the burner. The hot side of the pot makes the liquid rise to the surface, it flows across the top of the pot, and descends on the cool side, so there's a steady circulation.   Periodically, I add more water, skim more crud, skim more fat.  You can set it up so there's a sort of steady state, and leave it overnight.

Finally, you've run out of patience. I strain all the (thoroughly soggy) vegetables and bones using a chinois  ( a conical strainer) into a big plastic container (mine's a standard Cambro).  This always seems to be a messy process, whether you're ladling the liquid into the strainer, scooping the solids, or pouring the whole thing out.  Ultimately, though, the big pot is empty, the liquid is in the Cambro, and you have a pile of cooked bones and vegetables.

I pick out the more obvious vegetables, then load the stock pot again, with fresh mirepoix vegetables: Get the pot hot, add some oil, dump in the chopped vegetables and soften them up a bit, maybe just as they start to caramelize, dump all those bones in, add water, and repeat.  This second extraction pulls more of the gelatin and flavor out, but generally isn't as dark or flavorful as the first extraction.

Meanwhile, the liquid from the first extraction can be cooled down and you get another chance to skim the fat.  The picture is showing the fat layer on the remoulage (second extraction), but it looks the same on the first go-around. I pour off the liquid, making sure not to disturb the particulate crud in the bottom of the container. 
 

 I then reduce the liquid a bit more - maybe by half? and then get ready to do the final filtering.
In theory, there are techniques using egg whites and such to remove the particulates, but I've found that filtering through plain white paper towels works pretty well.  For my next batch, I'm going to try some fancy new fabric filter bags made for this kind of use.


 
I ladle the reduced stock through the filter (in the same conical strainer) - you'll see plenty of particulates, and the flow through the filter gradually slows as it gets plugged up. Once that's done, I portion it out into plastic containers to go into the refrigerator or freezer.

The second extraction works the same way - strain it, reduce it, filter it. Here's a picture of the remoulage being portioned out and you can see how gelatinous it is at refrigerator temperatures.  That gelatin is what makes for a that wonderful unctuous mouth feel when you use a good stock.

 

Overall, from 10 pounds of bones, I wound up with about 2 liters of first extraction, and 1 liter of second extraction.