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A Simple Stock-Simmering Question . . .

Should the stockpot be covered or uncovered during the long simmer?

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  1. I usually keep mine covered - to prevent a lot of humidity in the kitchen and to prevent rapid evaporation.

      1. I say uncovered. You'll lose volume but that's partly what you want - what I'll call "partial" concentration. If it gets too low, just add back some water.

        1. It depends...do you want to concentrate the flavor and reduce it? Then uncover it. Do you want about the same amount of liquid at the end as you had to begin with? Then cover it.
          I keep mine covered after I have skimmed the scum off the top.

          1. Uncovered. I've done it both ways, prefer uncovered for more flavor. Covered keeps the evaporation dripping right back into the pot, which dilutes the flavor IMO.

            1. Uncovered. THat's the way I learned at school and at work. So that's what I do at home.

              1. If making the stock in the pressure cooker, I used the lid. :)

                In a conventional pot you could use either way. Without the lid you'll get a bit more evaporation, and concentration. With a lid on, you can maintain heat with a lower flame. Often I find that when I look at a covered pot, there is some boiling, which quickly dies down as heat escapes.

                I suspect that if you maximize clarity you should leave lid off. This lets you watch the pot, and set the flame so bubbles barely reach the surface. But if you want to minimize heat and moisture loss, use the lid. I usually use the lid.

                Lid off may also produce a lighter colored stock since the surface of the stock does not get as warm. A way to maximize color would be to cook it in a covered pot in the oven (dutch oven in the oven).

                Concentration ultimately depends on the liquid to solids ingredients ratio at the end of the cooking process, not the ratio at the beginning. You could start with more water and let it reduce. You could start with less (but enough to cover), and recycle it via condensation on the lid.

                1. There are no simple questions when asking the internet for answers...

                  I do it both ways depending on the stock I'm making:
                  White chicken stock - lid on
                  Brown chicken stock - lid off


                  1. Uncovered: stocks are usually simmered to reduce them and to concentrate the flavors.

                    3 Replies
                    1. re: Sam Fujisaka

                      Plus, uncovered makes a house smell like a home.

                        1. re: Veggo

                          The house began to smell like a home shortly after the bones began roasting. Because I liked all of the reasons for each of your preferences, my veal stock is presently simmering partially covered.

                      1. Uncovered, you want it to reduce and intensify in flavor. Also as I have learned reading Thomas Keller SKIM, SKIM, SKIM.

                        3 Replies
                        1. re: rezpeni

                          So how much does it reduce? Typically, how much water and solids do you start with, and how much stock to do you end up with once you've strained the solids out?

                          My inclination is to focus on extracting flavor the first time around, and then worry about concentrating flavor during a second stage of cooking. I might leave the large bones in the stock during the second stage.

                          Reduction to a glaze is yet another step.

                          1. re: paulj

                            I would say the liquid reduces by about 1/3 but I never go by how much it reduces I go by the taste. I keep tasting, tasting, tasting, until it tastes right you can really tell when it changes from a kind of flavored water to stock, it's a real eureka moment and the difference between the two can take place in as short as a half hour it seems (after cooking 3-4 hours). I've been doing a roasted vegetable stock using roasted carrot, onion, celery, leeks, garlic, depends on what I have around. It is incredibly rich and a great substitute for chicken stock.

                            1. re: paulj

                              What matters is your end use of the stock. If it's for a hearty stew with deep rich flavours then uncovered with reduction is what you want. On the other hand if you want a lighter flavour then perhaps it's lid on to achieve those results.
                              I do it many different ways, and sometimes roast the bones / veg, sometimes I reduce the stock to a sticky glaze.

                          2. Uncovered for temperature regulation. A covered pot will eventually gain heat and your simmer will go beyond a simmer

                            1 Reply
                            1. re: bellyspeaks

                              That just comes down to controlling your stove / having your pot on the right burner etc...

                            2. Is there a time limit here--I read about simmering 24+ hours-- surely you're gonna get all there is out of those bones after 2-3 (4?) hours? Also, bubbles *should* break the surface--is that right? Or is it okay to just sit the bones in very hot water for hours?
                              I simmered my turkey 'tovers with vegetables. It seemed silly to reduce the stock any longer if I would only have to add water again later. No rules here, right ?-- or am I missing something?

                              18 Replies
                              1. re: BangorDin

                                I usually do 24-36 hours. You'll get the flavor from less but you get the collagen and really *rich* flavor from a long, slow cooking.

                                Mine isn't concentrated -- I end up with about the same amount of liquid that I started with. But it is very flavor and color intense. Closer, perhaps, to a demi-glace.

                                1. re: rainey

                                  rainey, how do you do your stock,,,,,demi glace....very interesting, could you share from beginning to end what you are doing....how much chicken, what kind of chicken
                                  backbones only or whole hen, amount of water, flavourings,,,,,etc
                                  some say that the veg should only go in the last hour of simmer or if they stay though the process they become bitter and take away from the flavour.
                                  thanking you for your info

                                  1. re: heylids

                                    Mine is a very simple formula: whatever's left over* + onion, celery, carrot, parsley, a leek if I've got one, a clove of garlic, whole peppercorns and some salt. It all goes in a slow cooker if it fits, a stockpot if it doesn't. I add as much water as it takes to cover the solids and simmer with the cover displaced enough that it vents.

                                    I let it go at the lowest temp that will result in a small amount of movement on the surface for 24-36 hours -- this is the part where you want a cooktop with a great simmer. Then I strain everything off (the dogs love this stuff) and let the fat coalesce on the top of the stock in the fridge so I can remove it. What's left is what I use for soup adjusting it by reducing to concentrate flavor or seasoning. And I add fresh veggies for the soup.

                                    I've never had any bitterness from overcooked veggies. In fact the veggies that flavor the stock are pretty yummy. They're just babyfood by that point so the dogs get 'em.

                                    As I understand it -- and it's only a general popular knowledge sort of understanding -- the demi-glace aspect comes from the collagen (or whatever) that comes from the bones over the course of the long simmer.

                                    If you want a crystal clear stock you can use this fascinating technique: http://www.nytimes.com/2007/09/05/din... But I'm a home cook who does real food so I don't. ...other than one fascinating time when I had to try it out. ;>

                                    * That could also be whatever's been collecting in the freezer as I keep things I don't use like wing tips or breast bones, etc until I've got enough to bother with.

                                    1. re: rainey

                                      rainey, checked out your link, go figure, what will they think of next.
                                      I make my stock much like your but read that if the carrots and celery stay in too long they get bitter.....so I was thinking out taking them out soon next time...maybe not. I am also now wondering what is a simmer, should you see the bubbles.....someone said just the shimmer of movement. I like to make my stock over night and don't have the best stove, temp goes up then down but at the very lowest it is just a shimmer and I thought that would be too low.....more thoughts....

                                      1. re: heylids

                                        I don't want to see bubbles tho I can't imagine small ones that don't come too fast would do much harm.

                                        Not sure why veggies would get bitter if they aren't allowed to burn.

                                        If you have spikes and dips on your cooktop have you tried a slowcooker? I'd rather do stock in a slowcooker but the one I have just isn't big enough for a turkey carcass.

                                        1. re: rainey

                                          I always heard this about vegetables (specifically carrots) but it never stopped me from putting them in from the beginning. Never tasted any bitterness, and always wondered why people say that.

                                2. re: BangorDin

                                  Yes, bubbles should break the surface.

                                  1. re: sarah galvin

                                    There is no evidence that this has any benefit. In fact, as long as you're above the temperature at which collagen turns to gelatin, a lower temperature would be better. I do my stock in a low oven (200 degrees) so there is no chance of bubble formation.

                                    1. re: jeremyn

                                      jeremyn, do you keep a lid on it when it's in the oven,,,,,never heard of the oven method thanks of tip

                                      1. re: heylids

                                        I do keep a lid on it, but doing so isn't necessary. If I left it uncovered, I would increase the temperature slightly since evaporation would lower the stock temperature. The important thing is checking it with a thermometer once it's reached equilibrium (at least an hour). I like a temperature somewhere between 180-200 degrees.

                                  2. re: BangorDin

                                    I haven't cooked stock for longer than a few hours, but have read that the calcium leaching from the bones in really prolonged cooking can make the stock bitter. I start it covered, so all the ingredients remain submerged, then when they have given up most of their flavor, I uncover the pot and taste periodically until the volume reduces enough for the desired strength. If making a concentrated stock or glace, I strain out the solids before cooking the finished stock down farther.

                                    1. re: greygarious

                                      I cook stock for a long time and haven't noticed any bitterness.

                                      1. re: jeremyn

                                        I don't cook my stock any longer than six hours, but I do put the whole pot in the frig overnight. It brings out the gelatin, then I can heat enough to strain out the bones and veggies. I have never noticed any bitterness from the celery or carrots. Mine is a covered stock. I think it is so interesting that everyone has their own method and it works for them!

                                        1. re: MartiniGenie

                                          I think covering or not might have a lot to do with the particulars of how your individual stove and pot cooperate to reach the desired temperature! I (regrettably) have an electric range now, and it's low/simmer setting is verrrry low, so with a medium-weight IKEA pot, I have to keep the pot mostly covered (lid lightly ajar) to achieve that magic ~200 temperature stably for many hours.

                                          1. re: MartiniGenie

                                            That's interesting.

                                            You're saying that you can get the gelatin + the lighter color and -- I assume -- the full-bodied flavor from a shorter cooking + a longer rest -- with the bones & aromatics? -- in the fridge. Is that the concept?

                                            I want all the flavor or a long simmer and I accept the dark color as a consequence. If I could have both I'd be a happy camper indeed!

                                            1. re: rainey

                                              I have the darker color due to the yellow onion skins that I add to mine. I save all my onion skins, celery hearts and leaves, cabbage hearts and any discarded outer leaves and carrot ends and peelings in the freezer along with the bones from roasted chickens. When I fill up a gallon freezer bag, it's time to make stock. Learned about what to put in stock when I was working with some chefs as a kid. One had trained in Germany; the other in New York.

                                              And yes, I guess the concept is as above. The refrigerator method just kind of occurred as a result of me having to leave the house and not wanting the pot on the stove. I noticed the stock had gelled up when I pulled back out of the frig.

                                              1. re: MartiniGenie

                                                I cook my stock the exact same way (accumulated veg bits and bones), and I often simmer at 200 for only around 6 hours, and then strain and cool. With even just a few bones, it gels quite thick after this amount of simmering, even with the bones removed before cooling. So, I suspect that it's not so much pulling gelatin out while it's sitting in the fridge, as it is gelling from what had already cooked out in 6 hours.

                                          2. re: jeremyn

                                            I've never noticed bitterness from either the bones or the aromatics before either.

                                      2. I consider mine covered but, in truth, I offset the cover enough that steam can escape. That prevents the pressure buildup that causes sputtering and spills. It also keeps the stock from getting to a boil -- for good stock you don't ever want to see bubbles, just the slightest shimmer of movement on the surface.

                                        1 Reply
                                        1. re: rainey

                                          That's what I do too, middle of the road. If it starts bubbling too much, then the lid comes off, I just want to see a bubble or two at a time. Then when it's done, I turn it off and leave it completely covered for an hour or two to cool down a bit but still infuse a little more before chilling.

                                        2. Are any of the nutrients evapoating out with the water when the lid is off? Also, any reason to not throw egg shells in the stock 'scrap bag'?

                                          12 Replies
                                          1. re: evoldog

                                            No, the nutrients stay right there in the stock (although they may be degrading in the long cooking process) -- the only thing that evaporates is water.

                                            The only reason you might want to not put eggshells in the scrap bag is because there's a better way to put them in the stock.

                                            After your stock is cooled (and defatted if you like) -- mix the egg shells with a lightly beaten egg white and stir into the stock. Bring the stock to a rolling boil for 5 minutes, then strain through a fine sieve lined with cheesecloth.

                                            The particles that make your stock cloudy will stick to the now-cooked egg white and shells...so when you strain out the egg white and shells, you'll be left with a lovely nearly-clear stock. (Tastes a little clearer, and looks prettier...depends on how I'm using it as to whether I clarify the stock or not.)

                                            1. re: sunshine842

                                              Two things:
                                              1) I'm curious about "degrading in the long cooking process". What exactly does that mean? I've read that the veggies will turn to mush and be useless, but that the nutrients remain in the stock...what are the determining factors and defining scale relative to the degradation of nutrients over time of simmering, other than from evaporation?
                                              2) As a kid in the 60's, I remember Welch's Grape Jelly commercials that boasted their jelly tasted better because the flavor stays in due to the closed system. It had Fred Flinstone, I think, and the cartoon jelly cooking contraption looked like a still, with the steam - and supposedly the flavor (nutrients) of the jelly - not being released, but returned to the mix. Seems like the same would hold true with evaporating stock, that some of the nutrients would escape with the steam, if left uncovered.
                                              As an aside, (and these are observations of a newbie, I'm still working on my "Junior Kitchen Bitch Badge") concerning the argument that lid off makes it stronger - I would theorize that is only due to evaporating water, and that starting with the water at the same level as it would end up at with the lid off, but leaviing the lid on, that you would end up with the exact same concentration level but somewhat higher, if I'm correct about retaining some of the nutrients that would have been lost with the steam were the lid off; but that definitively, the lid on system would produce a more concentrated stock, relative to maintaining a similar water/solids ratio.
                                              Oh yea - I forgot about the eggshells - I make wine, so I'm familiar with their clearing properties..I'm more after substance than form in my stocks, they go to chicken soup and this is grub that just I'll be eating, so taste is paramount. I just wanted to know if, like some leaves and things like brocoli, could the shells be a detriment...and if not, what do they contribute?

                                              1. re: evoldog

                                                I don't think you should think about stock as a way of getting nutrients from vegetables. Very long cooking probably extracts nutrients, such as calcium, from bones. And it is a good way of getting collagen and gelatin. But otherwise, fresh vegetables are a better source of vitamins.

                                                Clear stock probably has less nutrients than a cloudy one - something gets thrown away with the egg raft.

                                                I suspect the real difference when the lid is on, is that the stock is more likely to boil. With less heat loss to the air, the stock will get hotter - unless you compensate with the heat level. If you want to maximize clarity, then cook without the lid, and carefully monitor percolation through the egg raft. But if you are just seeking to maximize the extraction of flavors from the solids, a lid is ok. Shoot, go all the way, and cook it under pressure.

                                                1. re: paulj

                                                  Or find a happy medium and keep the lid cracked a bit.

                                                  1. re: monavano

                                                    Yes , yes, YES! It makes a tremendous difference to leave a small gap.

                                                    You'd think that you'd have more evaporation but it inhibits the boil enough to save a lot of loss and improve the flavor and clarity.

                                                2. re: evoldog

                                                  It's important to distinguish between "nutrients" (vitamins, minerals, etc.) and flavour compounds.
                                                  Everything that's not water will essentially remain in the stock, be it flavour, fat, gelatin, or whatever nutrients are left over after a long simmer. Once the bones and other stuff have given all their flavour to the stock (after one, two, ...eight hours, depending what kind of stock it is) then the only way to further concentrate the flavour without adding more bones is to reduce it; and the only way to reduce it is to evaporate the water (i.e. lid off.)

                                                  If I have a chance I'll go bust out the ol' Merck Index and see if I can't find some data on the temperature stability of things like vitamin C and so forth... but at 1AM I can't say I have the energy. ;)

                                                3. re: sunshine842

                                                  Through add't'l i-net searches, I've found that the water soluable nutrients DO escape with the steam...anybody have anything definitive on that, and nutrients/flavor lost to heat, etc.

                                                  Ideally, I'd like to know exactly what does what so I can plan my stocks accordingly.

                                                  At present, I'm making stock only for chicken & veggie soup, and I have a gas stove that controls the temp perfectly, so I can maintain a 'shimmer-no-bubbles' state indefinitely.

                                                  I completely crush all bones with channel lock pliers so the marrow gets full exposure.

                                                  I bring to a boil rotissorie chicken carcass, grilled necks and backs, bones and skin from grilled leg/thigh quarters, and raw feet in water covering it by 1 inche, reduce it immediately to simmer and leave 12-24 hours covered, skimming occasionally.

                                                  Then I add in onion, celery, carrot and garlic (I LOVE garlic), any other veggies and contents of veggie scrap bag from freezer I have handy (other than broccoli and others that I've read don't do well) and a shitload of different spices, add more water to cover all and let it simmer still covered for a cumulative total of around 36 hours.

                                                  I then strain the solids out and start a soup by adding in whatever new veggies I want in it, and towards the end, the chicken removed from the whole rotisserie chicks and the leg and thigh quarters. I try to not cook the chicks all the way, so that they can stand a little more "pot time", and restrict their heating in the soup to 15-20 minutes, so as to retain flavor in the bites, and in consideration of reheating.

                                                  My thinking is that since it ends up as soup anyway, that I gain nothing by reducing it way down - I'm just going to add water back to it to get soup. I said I start with 1" of water - I'm working towards just enough to keep it covered, and when it is to become soup, I add what water it needs to taste right.

                                                  Point is, I see no reason to risk loss of nutrients, flavor or whatever by cooking uncovered, as there doesn't seem to be any actual gain from doing so, unless you're going for a demiglaze.

                                                  Soooo, I guess I'm looking for the following, applicable to my end use as above specified:

                                                  1. What do you lose that escapes with steam if uncovered (when it's covered I don't have to wake up in fear at 3 a.m. worrying about it needing water that escaped if it was uncovered);

                                                  2. What do you lose from heat degradation;

                                                  3. Is my basic procedure proper, and if not, in what way;

                                                  4. Are there any drawbacks to 36 hour simmering (again, my stove maintains proper temp perfectly);

                                                  5. Bubbles breaking surface or not;

                                                  6. A comprehensive list of things like broccoli that should never be used;

                                                  7. Suggestions relative to the "soup phase", such as how long is too long and/or what is the proper period of time, and should it be at same temp as the stock. Since it will be covered, nothing is lost with the steam, so that leaves heat degradation - how does that affect? Currently, I'm simmering teh soup for 12-24 hours prior to adding the chick meat, adn I don't care if the veggies turn to "mush", I'm only concerned about nutrient and/or flavor loss from overcooking.

                                                  8. Any tips on conning some sucker into de-boning and bone crushing? The rest of the process is pretty "Wine Friendly"...8-)

                                                  1. re: evoldog

                                                    I'm thinking you're about 28 hours overcooked by going for 36 hours.

                                                    By that point, everything is cooked to death and then some...and the flavor and texture (and any chance of nutrients was gone yesterday)

                                                    Try it at 6 hours or so and see if it doesn't taste a little brighter...there's a reason none of the classic cookbooks (Julia Child et al) don't recommend that long a simmer.

                                                    1. re: sunshine842

                                                      Hmmmmm....I'm thinking that upwards of 90-95% of everything I've read says longer is better...do you have any numbers relative to harm done by longer than 6 hours? Besides, I just got three pots simmering 30 min ago, and I'm ready for bed...I'd hate to have to get up at 2 am to turn it off..almost as much as I'd hate to ruin it by over cooking...I haven't done many, and the first batches I did only went for a few hours, and they seemed OK, but then so did the 36 hour ones...I'm too new at it to tell...

                                                    2. re: evoldog

                                                      Does your stock pass the knuckle test? Rap a refrigerated container of the stock with your knuckles? How does it jiggle? I have quart of stock that I made yesterday from a 6lb chicken; it's just a bit looser than a jello salad. For chicken that's pretty good.

                                                      For that I cooked the gibblets (no liver) backs and wing tips for 20 min in the pressure cooker; added the other parts and cooked those till tender; removed those parts and saved the meat, returning the bones and skin to the pressure cooker; finished with another 30 minutes at pressure.

                                                      1. re: paulj

                                                        My understanding is that it gelling is relative to factors other than long cooking or whether it was covered or not; I'm thinking it mainly had to do with not boiling it too long, adn I'll need you to please explain how that comes into play here, as I don't see it.

                                                        1. re: evoldog

                                                          Do I have access to scientific research? No.

                                                          Am I even interested enough to go Google it? No.

                                                          Do I think it's significant that EVERY major cookbook author of the last century recommends 4-6 hours? You betcha. If they thought it was better if you simmered it for 36 hours, somebody would have put out a recipe that said so, and there'd have been some weird long drawn-out conversation on Chow about it.