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Dec 27, 2010 08:35 AM

Will Someone Please Explain Vacuum Sealers and Uses?

I "get" sous vide cooking. I have--and regularly use--a cheapo FoodSaver for packaging and storing ingredients and food. And I even use a Vac-U-Vin canister (manual pump) for marinating.

Here's what I DON'T get: Since liquids don't compress or expand under vacuum, why would anyone buy a $$$ vacuum bagger for sous vide or any reason other than storing down comforters and sweaters? It seems to me that once the air is drawn out of the food bag, that's it--no vacuum, and no expansion of the food inside. In contrast, using a chamber with an airspace to which the food at least partially exposed, seems more likely to "open" the food, allowing some of the marinade to go deeper into the tissue.

Who can explain why one would need a $3K sealer for packets when a Ziplock would appear to do the same thing?

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    "Vacuum packaging prevents evaporative losses of
    flavor volatiles and moisture during cooking and inhibits
    off-flavors from oxidation"

    "Vacuum sealing also reduces aerobic bacterial growth
    and allows for the efficient transfer of thermal energy
    from the water (or steam) to the food."

    And you don't need a $3,000 sealer, a $50-$100 sealer works well.

    5 Replies
    1. re: ferret

      ferret: Thanks. All these things can be accomplished by using a ziplock without pulling any vacuum at all, right?

      1. re: kaleokahu

        It's not the vacuum, per se, it's keeping contained air at a minimum - you want to submerge the food, not have it float in a bag.

        1. re: ferret

          ferret: Thanks, that's what I wondered. Just burp the ziplock and you're good to go.

          Now, since I'm asking silly questions, why not maintain a small, DRY environment for the food within the bath, e.g., a dry rub on the food, in a small vacuum container, suspended/anchored in the oil/water bath? Seems like it would just take a little longer to come to temp is all, and you might end up with a better steak.

          1. re: kaleokahu

            Totally not following you. I'm definitely not an expert in this area (or even a knowledgeable novice) but from what I understand, the goal is to keep the food cooking at a constant temperature without a lot of fluctuation. The way to achieve that is to have maximum exposure of the food to the water bath. That is achieved by immersion and absence of air pockets which would tend to insulate the areas that aren't in contact with water.

            The sous vide steak preparations that I've seen all cook the steak to temp and then do a quick sear on the outside. You can certainly add seasoning at the sear stage. What you propose doesn't even approach the sous vide concept.

            1. re: ferret

              ferret: Sorry if I'm not being clear. What I have read elsewhere is:

              "The basic concept of sous vide cooking is that food should be cooked at the temperature it will be served at. For instance, if you are cooking a steak to medium rare, you want to serve it at 131 degrees Fahrenheit."

              I understand that the water/oil bath is desirable because of the huge thermal mass the liquid provides, as well as the extremely tight temperature control. But is food-bagged-in-liquid-cooked-in-liquid NECESSARY to be true to the concept?

              I mean, really, is a small, dry, sealed vacuum container suspended in the same water bath going to break some rule, or not come to the same temperature in short order (and what does "insulation" really mean in 24-to-72-hour cook times?)?

              Of course you can season after the sear, if all you wish to season is the food surface. But I regularly apply dry rubs to steaks as a "marinade", and remove it prior to the sear. Why wouldn't the same be as efficacious over the time usually spent "under water"?

    2. It's nearly impossible to get all the air out of a zip-top bag. If you've got something that's completely submerged in liquid, then sure - you can just burp it. But if you're trying to seal up a chicken leg quarter or some beef spare ribs, you need the vacuum to pull the plastic into - and force the air out of - the interstices.

      The sous vide method often involves cooking foods in little or no liquid. A vacuum sealer comes in very handy.

      But that doesn't mean you need to spend a fortune. The really high-end vacuum sealers tend to use industrial wrapping rather than the (expensive) proprietary packages you can get at your local Target. If you're sealing up a few hundred pounds of product a day, then the big unit is the way to go. For occasional home use, a FoodSaver does just fine.

      4 Replies
      1. re: alanbarnes

        alanbarnes: Thanks. I see what you mean about irregular shapes in bags being more likely to trap air. But other than flotation problems, what's bad about a little air in the bag?

        1. re: kaleokahu

          I suppose that when cooking sous vide an air pocket might create some insulation that would result in uneven cooking. But my main reason for using a vacuum sealer is for long-term low-temp storage, where a little air leads to a lot of freezer burn.

        2. re: alanbarnes

          I actually take a rather dim view of the usefulness of a home vacuum machine in sous vide cooking. When I first got into sous vide, I put a food saver on my wishlist. But messing around with ziplock bags, I eventually decided I didn't really need one.

          You can get virtually all air out of most bags by submerging them in water and working the bag a bit before sealing. This works for all but the most irregular of food shapes. Most items can either be packaged individually or broken down into regular shapes without hurting the dish - the only thing I can think of that I've tried and had problems with is cauliflower, though I'm sure there are others that would be problematic, especially other vegetables.

          In the interest of full disclosure, I do occasionally notice VERY small air bubbles in the bag after closure. But I haven't found that tiny air bubbles cause any significant problems, though I could see how they might if you're really pushing the low-temperature and time boundaries for a known dangerous item like chicken. I also don't do any long term storage in the freezer of sous vide foods, so take that into consideration.

          A big downside to home vacuum sealers is the inability to cook with liquids in the bag without freezing first. Low temp poaching in small amounts of olive oil has been one of my favorite things about sous vide cooking, and a food saver would make this more of a hassle. I also at times cook in a marinade or just a bit of some wet ingredient or another (lemon juice, soy sauce, etc)

          Also of note - I don't use a sous vide supreme, and I'm not sure if that set up allows for the tops of bags to be out of the water. I typically keep the zipper of a ziplock out of the water because I've found that makes for MUCH less risk of water leaking into the bag during cooking.

          A chamber vac, on the other hand, would be very nice... someday.

          1. re: cowboyardee

            cowboy: "You can get virtually all air out of most bags by submerging them in water and working the bag a bit before sealing. This works for all but the most irregular of food shapes."

            Thanks for saying that, verifying what I thought was common sense.

        3. For openers, no, ziplock bags do NOT have the integrity required for a true "air tight" seal. To get that you have to heat seal the plastic tube at both ends. Vacuuming out the air is important too. Any air left in the bag can promote bacterial growth as well as promote freezer burn in long term freezer storage. The weight and quality of the plastic film is also very important. The thinner the plastic film, the more "air permeable" it is. The long and short of it is get a good vacuum sealer, buy reliable quality heat-safe bags, learn how to use the equipment well. And don't waste a dime on those hand-pump vacuum seal systems. If you want one, I'll send you mine. They suck and are 110% unreliable. Maybe more. '-)

          12 Replies
          1. re: Caroline1

            Hi, Car: Thanks for the good advice. I was mostly talking about what happens in the cooking, not in food preservation.

            Re: bacterial growth... I forget the FDA/USDA tables, but isn't the idea that even low, sous vide temps--if they're held for hours--are enough to kill the danger bugs? If that's the case, and you're sealing your bag/container right before it goes in the bath, what difference does a little/lot air make?

            Re: the manual systems... At the time that I bought the Vac-U-Vin winestoppers, I also got several of the round plastic canisters that accept the same stoppers. The canisters are thick and have silicone gaskets. They'll hold a vacuum for weeks, and depending on how you pump, they'll draw a stronger vacuum than my electric vacuum sealer. I've used them for several years now to store herbs and coffee, but the best use I've found for them is for marinating. An hour under the vacuum is the equivalent of overnight in a baggie in the 'fridge.

            My OP was prompted by what appears to me to be either a misnomer or an impossibility with regard to "sous vide". Other than merely voiding air, the vacuum apparently serves no purpose. This is unlike what I've experienced with partial-volume marinades under moderate vacuum. So THAT prompted my strange proposal about dry-yet-submerged sous vide.

            Hope Y'all had a nice holiday and your plumbing's all fixed.

            1. re: kaleokahu

              The problem with bacterial growth is that sous vide cooking can involve pasteurizing foods at the lowest temperature that will get the job done - and tiny air bubbles effectively slow heat transfer to the surface of the food, making for food that isn't effectively pasteurized. If you pasteurize a protein at 131 F, an air bubble might make whatever portion of food that air bubble is touching cook at a lower temperature (say ~120 F which does not effectively pasteurize at all), which could in theory be dangerous.

              Now, in practice, I haven't found this to be a major issue. But that is at least in part because I have factored it in. I use a delta temp for almost all short preparations of meats (say, cooking in a 140 F water bath but pulling the food out when the center is still 125 F) or else sear at the end, and I don't do long cooking times at temps below 135 without searing first and handling cleanly.

              1. re: cowboyardee

                cowboy: You are a wealth of information as always, and an actual DOER of sous vide. I am but a neophyte with this kind of cooking.

                "If you pasteurize a protein at 131 F, an air bubble might make whatever portion of food that air bubble is touching cook at a lower temperature (say ~120 F which does not effectively pasteurize at all), which could in theory be dangerous."

                I totally agree with that, in theory. But if you have a bubble (or even a few cubic inches) of air in a bag in a multi-gallon 131F bath for 36 HOURS, isn't EVERYTHING in the bag--air included--going to be 131F for about... 35 hours?

                1. re: kaleokahu

                  Air does not conduct heat effectively (and in a confined space it insulates). To get the areas of the food that are not in contact with the water to the same temperature as those touching the water you need to heat the air to a higher temp. So effectively, the air bubbles cause those areas to be cooler than 131F (as per your example).

                  1. re: ferret

                    ferret: OK, admittedly I know nothing about sous vide. I really don't mean to be contrary here.

                    But I know that if I put a big 'ol joint of meat in a tray in my hot smoker set at 131F, EVERYTHING in the smoker'll get to 131F within 24 hours: meat, liquor, aromatics. air, tray, grates, the whole shebang. By the time you make it to 36 or 48 hours in a 131F bath, nothing's gonna be alive except for those 2 bacteria that live in the deep ocean volcanic vents. These water/oil baths, being such huge thermal masses, will equalize things even faster than that. One little bit of air can't possibly hold the adjacent food at a lower temp than the surrounding liquid for very long, dont'cha think?

                    1. re: kaleokahu

                      The truth is... I don't know. I can tell you that I've never come across a section of protein that seemed any less cooked than the rest after a sous vide bath, tiny air bubbles or no. And I suspect that given enough time, the temp within the bag is quite uniform, air bubbles or not. But I don't have any great way of testing individual spots on the surface of a piece of meat, so I don't know exactly how much of a difference it makes in terms of how longer it takes for meat under an air bubble to come to temperature. Long enough and staph toxin could be an issue, even with prolonged cooking after the entire bag's contents reach 131 f. I even worry that along with the slower conduction through air, an air bubble could create minor evaporative cooling on the surface of the meat, but my logic may be off there. And beyond that, there is the notion that air allows aerobic bacteria to better thrive and reproduce while the food comes up to temperature, potentially making pasteurization trickier.

                      Part of the issue is really just that cooking at 131 is really about the minimal temperature that effectively pasteurizes in the first place (and even then, things like chicken need a higher temp to pasteurize). So while it might not make much of a difference, there's not much wiggle room either. I'm already taking a minor leap of faith that my water bath has adequate circulation and that my thermocouple isn't reading just a hair high (both tested with a thermapen, but still).

                      So to reiterate - tiny air bubbles have never made a discernible difference in my experience with sous vide (and again, with ziploc bag sealed under water, we're talking tiny air bubbles if they're there at all). But I take extra precautions anyway.

              2. re: kaleokahu

                Okay. I'm starting all over. I don't know why, but very very very often when I'm writing a post on Chowhound, SUDDENLY it disappears! No retrieving. Starting anew is the only option. Pisses me off. ONLY happens on Chowhound. So just to let you know, I'm starting again. <sigh> I will respond on a reliable word processor, then cut and paste my response, so if this reads pasty, you know why.

                Now, about cooking and long term storage and air and sous vide... Despite some public misunderstanding to the contrary as a result of a bad Sous Vide Supreme infomercial, sous vide is NOT a rapid cooking method! Takes hours and hours. Sometimes 24 (or more), so with that kind of cooking time, who does one or two portions at a time? You do some for now and a BUNCH for later! Your freezer is your friend. Add to that the fact that rapid cooling after the sous vide bath is finished is critical to long term food safety, whether through refrigeration or freezing. Sooooo... The obvious most efficient and safest solution is to get ALL of the damned air out before you start and you're good to go. Ever done a bout with food borne illness? Get the air out!

                I also admit that I am not yet a well experienced sous vide practitioner. I'm still wrestling with whether I really want to turn that much space over to a counter top appliance that will likely not be used on a daily basis. I have found that when I store counter top appliances in the pantry, I tend to make do without them. I have a perfectly useless vented and thermostatically controlled deep fat fryer taking up a moderate amount of pantry shelf space where it smugly sits while I French fry in a saucepan. As a matter of fact, it turns out that I much prefer the saucepan, but can't quite bring myself to sending the fairly pricey deep fat fryer off to a new home via Goodwill. Maybe I'll donate it to an antiquated appliance museum some day. But not quite yet. So I'm thinking long and hard about five hundred bucks of metal and circuit boards hunkering down on my granite. What percent of my regular menu will lend itself to sous vide? Anyone have a great fettuccine sou vide recipe? Will sous vide be that much more interesting flavor and texture wise than poaching? I keep remembering my very expensive (1970s prices) pasta machine that lives in a cardboard box in the garage and hasn't seen the light of day in decades. I have no such resentment against my rarely used larding needle that takes up minimal space in a kitchen drawer, but we're talking fifteen bucks versus three hundred. Life can be such a quagmire.

                The plumbing disaster was survived, thanks for asking, though I do still need to hire someone to restore the damage the plumber did to my front lawn. The broken water main was followed five days later by a power failure/surge that wiped out my primary computer. It should be coming home in a few more days sporting a new 800gig hard drive, all covered by my $5.99 a month power surge insurance through my electricity vendor. All in all, I MUCH prefer doing without the great inconvenience of being forced to use this very quirky Dell notebook. Life does not always offer choices. Damn it.

                1. re: Caroline1

                  Car: Will you come visit me in the hospital when I leave a bubble in my bag?
                  "I don't know why, but very very very often when I'm writing a post on Chowhound, SUDDENLY it disappears! No retrieving. Starting anew is the only option."

                  I have the same thing happen, but I found a fix: When your draft poofs away, go right back to the post you were replying to, and hit "Reply" again, and you'll get everything back. It's worked for me!
                  Re the "quantity" sous vide thing... I get that, cooking in bulk and putting up changes the scales and longevity of things. Sure, there's a safety dimension to that. My few experiences with sous vide have all been in nicer restaurants. All I'll say is that if I EVER find out that the 36-hour pork belly in apple kimchee I paid $$ for was cooked in bulk days before, frozen and THAWED in a plastic bag for my pleasure, that place is off my list. Deep prep is one thing, leftovers-for-pay is a punishable offense in my book. What's next, scraping tonight's patrons' plates to make tomorrow's stocks?


                  Oh, and it's nice to hear you're getting something besides trouble from your power company. Happy New Year.

                  1. re: kaleokahu


                    Damn! THIRD try! And NOOOOOOOOO...! Reopening "Reply" regains nothing for me. It used to, but not since the last Chow renovation. Between this consistent problem and my recent computer problems, Chowhound is fast loosing its charm.

                    Anyway... Do you think there is ANY restaurant that serves sous vide anything that ends their work day by tucking bags full of pork belly, duck or scrambled eggs for the following night's menu? I don't think so! A freezer full of approximately a month's entrees makes much more sense! And I seriously doubt there is a soul alive who can discriminate between a frozen sous vide entree that has been in the freezer for a week and one that's been in the freezer for three months, assuming it's a good freezer. Maybe you've just lost a bunch of favorite restaurants? Poor baby! '-)

                    1. re: Caroline1

                      Car: "Do you think there is ANY restaurant that serves sous vide anything that ends their work day by tucking bags full of pork belly, duck or scrambled eggs for the following night's menu?"

                      There better be. Unless I'm stuck somewhere where there is NO fresh food to prepare, if I'm shelling out $$ at a nicer restaurant, they damn well better be serving me fresh and freshly prepared food. The reductio ad absurdum of this is Chef Bigpants from Chez Vide filling his cart from the Safeway freezer aisle with Wolfgang Puck's frozen Hockey Pucks.

                      I suppose I'll have to learn to ask: Has the plastic bag you cooked this dish in ever been in the freezer?

                      Re: losing its charm... You should see the e-mail I got recently from one of the pooh-bahs.

                  2. re: Caroline1

                    "Despite some public misunderstanding to the contrary as a result of a bad Sous Vide Supreme infomercial, sous vide is NOT a rapid cooking method! Takes hours and hours. Sometimes 24 (or more)"
                    Caroline, I'm not sure where you got this notion. I regularly cook things sous vide for an hour or less. My favorite way to cook chicken breast or most seafoods are short preparations.
                    Of course, there are plenty of long preparations as well, and these are some of my favorites.

                    As to whether sous vide is significantly different than poaching - I sure find it to be. The biggest factor is intensity of flavor, IMO, since poached foods inevitably disperse their flavors through the poaching liquid (and also into the air). But there's no shortage of other major differences.

                    Try for yourself:

                    Before you buy a large, expensive machine - do you have decent thermometer? Then try what I started off with. Fill a large lidded stockpot with water, bring it up to a specific temp and see how well you can keep that temp even on the stove. The idea is to fill the pot so that a hot bath will veeerrrrrry slowly lose temp at the lowest setting on your stove. Then turn your stove up just a hair, and you've got a stable water bath. Try a short preparation or two to get a feel for it. I've managed to keep a water bath within 1 deg F above or below my target for 24 hours this way, cooking pork shoulder for a wedding - I fell asleep for 6 hours and woke to find the temp changed less than a degree. It takes some fiddling to set up, but you might be surprised how stable a temp you can get on a stove top.

                    1. re: cowboyardee

                      I may be overreacting to the Richard Blais Sous Vide Supreme infomercial that comes on in the middle of the night. I couldn't watch it all the way through, there was so much misleading information being inferred and outright stated in the ten or fifteen minutes I did watch that I had to turn it off. I'm sure much of it was the result of editing because I'm equally confident that Blais would not intentionally mislead people. The problems for me were cutting the sous vide bag open, sliding out a browned piece of protein and not explaining that the browning was not the result of the sous vide process, yet frequently referring to the appliance as a "water oven." Hot air ovens brown, water ovens do not!. "Instant" meals were also referred to. I know that not all sous vide dishes require a day's cooking, but I also know that you don't cryovac something, drop it in the bath and expect dinner in ten minutes. Ain't gonna happen.

                      Thanks for the suggestion and instructions for stove top sous vide. But first I have to remember to buy some more bags for my vacuum sealer. Maybe actually listing them on a shopping list would help? Somehow I don't think Press'N'Seal will work as well. '-)

              3. Here's my .02, I only buy quantities of meats, fish, cheeses etc., that I can use in less than 4 weeks, so for me it doesn't make sense. I could never figure out the ad where they seal a wedge of cheese, why bother if you're going to open it again in a day or two.

                1 Reply
                1. re: treb

                  I bother because I save money when I buy in bulk. Living out of the country, much of what I purchase is imported so ... I use my vacuum sealer a lot. I also hate shopping so it's great to get it over with LOL!!! Humidity is a problem here so freshness is important.

                  When I prepare sous vide (amateur btw), so far I have only done it with fresh wild salmon without a real marinade. DH prefers the less is more thing, so a few fresh herbs, garlic, etc., and I freeze thin lemon slices before placing them on the salmon to seal; by the time I have the temp right for sous vide the lemon has thawed and it's perfect every time.