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Reducing stock (and I'm not talking economics)

c
CalgaryHound Jan 1, 2009 07:34 PM

I'm making stock from the turkey carcass from Christmas. Once I'm done with the carcass, can I reduce the stock by keeping it on the burner for a couple of hours so as to take up less room in the freezer?

  1. David A. Goldfarb Jan 27, 2010 05:26 AM

    Yes, certainly, it is common practice to reduce stock to concentrate the flavor and so it doesn't take so much freezer space. I usually reduce stock on a slow simmer by about half (this may take all day for a large pot, but it doesn't require much attention) after straining chilling, and removing the fat. The result should be thick and gelatinous when chilled. Then if you like, you can clarify it with egg whites.

    I used to boil stock down more vigorously, but found that when I did it slowly over a longer period of time, the flavors were richer, so I don't boil stock anymore to reduce it.

    If you reduce stock to one tenth the original volume, you have glace de viande, which is highly concentrated and can be used to add flavor to sauces and soups or quickly glaze sauteed meats or vegetables or as a rich sauce itself to drizzle over meat.

    If a reduced fish or vegetable stock is bitter, it usually needs salt, but don't salt until after reducing, or it will become too salty when reduced.

    1 Reply
    1. re: David A. Goldfarb
      mcf Jan 27, 2010 06:29 AM

      I just used a very concentrated seafood stock to make an unbelievably delicious seafood chowder the other day. I'd boiled it way down after a lobster feast, with addition of shrimp shells. No bitterness, just perfection, wonderful flavor. I concentrate all my stocks to save freezer space, and the flavors have always been excellent so far.

    2. t
      teigerdinner Jan 26, 2010 11:05 PM

      Tony cooking show says do NOT simmer carcass longer than 2 hours, do not boil stock aggressively--you lose flavor. So, I tried putting a cheap aluminum griddle that has gotten bowed down in the middle, over the pot, at a slant, end projecting beyond pot. Yup, good amount of water condensed, dripped off outside the pot, even at the very very low simmer this show recommends. So search for a "reducing lid" setup using same principle. Needs water reservoir on top to keep it coldish.

      Another option, a lid with a couple of tiny computer fans set in at edges, one aiming in at angle, then, `180 degrees away, one angled up and out. You would be creating a weak cyclone effect. THE PHYSICS CONCEPT in both cases is, lower the relative humidity (normally very high) in the air volume in the pot above the liquid. Then, seeing "a space containing more liberty--a Wild West for water molecules--molecules near the surface, even at the very low, flavor-retaining simmer, WILL opt for ESCAPE. Given one of these cheap tickets AWAY, the humidity near the surface will remain low, and more will follow. Voila--no long or ferocious boiling (alleged to be counterproductive), yet gentle removal of [some volume of] liquid. Does anyone sell a lid, condenser, etc. like this? Should they? Can you make a hokey one and experiment? Probably, yes, yes, and yes.

      One result so far--the heavy foil baking trays DO NOT work. Not enough heat-sink effect to do the condensation? Have not tried the fans approach yet.

      1. Caralien Jan 3, 2009 09:10 AM

        I usually start with the carcass in the Crock Pot (it's primary use) covered with a splatter-guard, remove the bones after awhile (or not, depending on my mood), then allow it to reduce to 1-2 pint-sized (marked & dated) mason jars kept in the refrigerator.

        a 20-30x reduction/concentration is standard for glace

        1. Romanmk Jan 2, 2009 01:04 PM

          You could go as far as to make "bouillon cubes". Reduce strained broth to maybe a 6th or 7th of it's original volume. Use very low heat when the liquid starts to get syrupy.

          1. d
            dmd_kc Jan 2, 2009 08:30 AM

            I reduce mine by a factor of about four or so, then freeze it in small batches (ice cube trays or individual zipper-lock baggies).

            Careful with vegetable stocks, though. I've had those turn bitter when over-reduced. I've never been able to identify any single culprit there, because I've had it happen with several different combinations.

            2 Replies
            1. re: dmd_kc
              m
              MakingSense Jan 2, 2009 12:35 PM

              Seafood stocks get bitter too. They lose their delicate flavor after about 20 minutes anyway so don't lend themselves to reducing. Maybe for heartier fish stocks, an hour. But after that, they get an off flavor. Best to freeze the fish frames and make them fresh.
              Oddly, I've had mushroom stocks get an off-taste too. Not as clear a flavor as I expected.

              1. re: MakingSense
                d
                dmd_kc Jan 2, 2009 10:20 PM

                I didn't know that about fish stock, but it makes sense somehow.

                I will never understand the unpredictability of vegetable stock. I've seen others blame celery, which I just can't believe is the culprit. I do believe it's necessary to make sure you don't make stock with anything you wouldn't eat -- especially no sprouted aromatics, which ARE often bitter on their own. The very worst one I've ever made came from roasted vegetables that tasted excellent on their own, but became completely inedible after 25 minutes in the water. That one may have been from too much carbon, but I dunno.

                At least if your vegetable stock goes bad, you aren't usually out much money.

            2. JoanN Jan 2, 2009 05:38 AM

              Absolutely. It's common practice. Recipes often direct that once strained and defatted (which I usually do in the fridge overnight), the stock should be brought to a vigorous boil and reduced by half. It's a good rule of thumb, but I usually just keep tasting until it reaches a point where I think I ought to be able to dilute it yet still have it remain flavorful.

              At the stage that you're reducing the stock, there's no reason not to bring it to a good boil so a couple of hours is far too long. Obviously, it depends on the volume, but you might well be able to reduce it to your satisfaction in as little as 15 or 20 minutes.

              2 Replies
              1. re: JoanN
                tzakiel Jan 27, 2010 04:26 AM

                Boiling stock makes it cloudy and can ruin the look of it for soups, etc. I've always been told to simmer it gently.

                1. re: tzakiel
                  JoanN Jan 27, 2010 05:49 AM

                  That's true for initial cooking of the stock, but not so much after it's been strained and defatted. Maybe I'm just not as fussy as some since I'm usually using the reduced stock for sauces. And I am very good about skimming and then straining through cheesecloth without pressing down on the solids. But in my experience, if the stock is clear of all impurities after being defatted, it will remain clear even after a vigorous boil.

                  That said, if I'm making something like a consomme where I want perfect clarity, I'll go all the way and clarify it with egg whites and additional lean protein.

              2. ipsedixit Jan 1, 2009 09:10 PM

                Reducing stock without the bones (and other goodies) will only reduce the volume of stock you have, it will not make the stock more concentrated.

                9 Replies
                1. re: ipsedixit
                  c
                  CalgaryHound Jan 2, 2009 04:27 AM

                  Is there any effective way to concentrate the stock?

                  1. re: ipsedixit
                    l
                    Liz K Jan 2, 2009 04:39 AM

                    Huh?

                    Of course that will concentrate the stock.

                    1. re: ipsedixit
                      thew Jan 2, 2009 05:30 AM

                      um - yes it will. water is boiling away. other chemicals remain. the ration of otehr stuff to water will increase.

                      if that isn't concentrating, i do not know what is.

                      1. re: ipsedixit
                        i
                        itryalot Jan 2, 2009 07:41 AM

                        I did that for Christmas with the beef stock and once I strained it, I further reduced it and it was definitely more concentrated. Anytime you simmer something, doesn't the water evaporate and you are left with more good stuff? I am an at home cook only, but Isn't that the principal behind demi glaces and such?

                        1. re: ipsedixit
                          k
                          KTinNYC Jan 2, 2009 08:56 AM

                          Please explain. If you are reducing the amount of water in the stock by reducing how are flavors not concentrated? Do flavors evaporate as well?

                          1. re: KTinNYC
                            ipsedixit Jan 2, 2009 09:47 AM

                            Maybe it does, but everytime I've done it this way the stock's flavor has been off.

                            If I want to reduce stock, I do it with the bones. Once the bones are removed, I no longer try to reduce.

                            1. re: ipsedixit
                              thew Jan 2, 2009 09:58 AM

                              the flavor being "off" certainly tells you that something is changing when it's boiling away on your stovetop. that something is concentration

                              1. re: ipsedixit
                                chowser Jan 2, 2009 10:06 AM

                                You could be more sensitive to the taste because when you boil longer, you do lose aromatics (which is why you smell it through the house) in addition to water. It's the same reason that people steam over seasoned aromatic water--because the aromatics also evaporate and can flavor whatever is being steamed.

                            2. re: ipsedixit
                              g
                              gfr1111 Jan 2, 2009 01:21 PM

                              Ipsedixit,
                              I always enjoy your comments. You know what you are talking about. But this time, I have to disagree. Boiling or simmering liquid does concentrate the remaining flavors.

                            3. todao Jan 1, 2009 09:06 PM

                              The length of time you can continue simmering your stock depends on how much stock you have, how much heat you apply, and what the ratio of liquids to solids there is in your combined ingredients. Simmering stock to reduce it and concentrate its flavors is a common practice but you'll have to be the judge of how long you can actually continue the process under your specific circumstances.

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