Water Displacement Method

robert.c.brown15

Hey Guys,

I am thinking about possibly buying the Anova Sous Vide Circulator which would be my first sous vide circulator and my first sous vide cooking experience, etc. Anyway, I had a question about the water displacement method. I have no plans to buy a foodsaver anytime soon and will never buy a chamber vacuum sealer. I also don't have room for a foodsaver. I will be using the circulator with a 5 or so gallon cooler and then using saran wrap to cover the top of it to keep the heat in/lessen evaporation.

Anyway, I understand the concept of water displacement as I've used it before to when freezing foods. For sous vide, I plan on hanging an open Ziploc bag over the edge of the cooler. That is correct right? I watched the video but wanted to make sure I'm understanding it correctly.

Also, I am looking forward to using sous vide with vegetables, along with steaks, etc. But are there certain foods, like vegetables, that the water displacement method will not work as well? Any limitations?

I do not want to buy any additional things such as foodsaver/ziploc hand pumps. I just want to use the bags I currently have in my cupboard for all my sous vide needs.

What do you guys think of all of this? Doable? Doing my best to not make sous vide a money pit. At least not yet! Thank you!

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Comments

prince_of_porcelain

I currently use water displacement for everything. I seal the bag up and drop it in the bath. It works very well for proteins and liquids, ok for most veggies, and not at all for coffee beans. No need to hang the bag over the side. I'd suggest checking the edge where the zipper closure meets the bag. I had a batch that had a sizeable hole there on every bag. But other than that one box, I've never had a problem. I use freezer bags. They are slightly more expensive, but worth it, in my opinion.

robert.c.brown15

So you seal the bag? Doesn't it float in the water then? Don't you want to avoid that?

Matthew_Snyder_68770

Submerge the bag all the way to the seal and seal it in that position. I've used this 'ghetto sous vide' in a pot on the stove, in a cooler and in my sink. Using the sink method makes it difficult to attach the bag to anything, so I prefer sealing completely.

Also, if you're using the pot on the stove method and cooking veg at a fairly high temp, there's a possibility of the plastic on the outside of the pot will start to warp and melt a bit. So it's better (imo) to seal completely and put the bag entirely in the pot of water. The only thing I've had a problem with floating was rapini.

And I agree, using freezer bags seems to work better imo.

Tim_Sutherland_52834

On a Cooking Issues podcast a while ago Dave Arnold had a response from Johnson & Johnson, A Family Company, that their ziploc bags were safe at 82C for SV. 82C was the temp in the question sent to J&J.

I cook-chill-store most of my SV so I always seal the bag as @Matthew Snyder describes. This ensures no liquid gets in the bag during the cooking and chill steps. It also ensures what is in the bag stays in the bag during storage.

Sealing the bag after displacement will reduce the chance of it floating. If your product has a tendency to float throw a few spoons in the bag.

prince_of_porcelain

Yes...should have stated that I seal the bag after submerging just past the zipper. Seal it 90% of the way first, and just the final inch or so after you submerge. Usually I just do this in the sous vide bath unless I'm running high temps with something that really wants to float. Then I'll use a separate pot of cool water so I can try to work as much of the air out of the bag as possible without also cooking my hands.

Tim_Sutherland_52834

Saute Tweezers are what you need to use to push the bag under water before sealing. They are also very useful in grabbing bags from the bottom of the hot bath. After a few uses you can SV without getting your hands wet.

robert.c.brown15

Thanks for all of the help. So basically anything I want to sous vide will work with this method right? Brian said most veggie and not coffee beans. I'm glad this works well with liquids. No reason to freeze olive oil or anything now.

Matthew_Snyder_68770

If I'm storing in the bag I cooked in, I tend to re-seal after cooking. The product almost invariably shrinks a little, and since there isn't a vacuum in the bag it will leave a gap otherwise.

ejf12009

Matthew, I would think that as long as your temperature/time combination was sufficient to pasteurize you wouldn't want to open the bag for fear of introducing contaminant into an otherwise sealed and sterile environment. Is this not the case, or is it just worth it anyway to get a closer seal?

I thought I had read (in MC?) that ziplocs were not suitable for cook-chill, though it seems like they should be adequate if the food is cooked to pasteurization and only stored for a few days...

robert.c.brown15

Yeah I've been wondering about the safety of if I use a Ziploc bag to cook something sous vide and then I want to chill in an ice bath and store it in the fridge, in the same bag. Apparently from what I am reading and hearing, doing that is safe.

And could someone explain pasteurization to me? In some posts it sounds like cooking something to pasteurization is optional. If you plan on taking something out of the bag and eating it right away then do you not have to cook it to pasteurization? But if you plan on throwing it in an ice bath and then the fridge you need to cook it to pasteurization?

Johan_Edstrom_5586

It has been up a few times, think beef that you can eat as

tartare you can cook and serve, cooking, chilling then storing and

re-heating without pasteurize can lead to serious bacteria development.

The time to pasteurize depends on protein, temp and size.

Here are some interesting links.

http://forum.chefsteps.com/discussion/comment/3093/#Comment_3093

robert.c.brown15

I have one more question about the NathanM charts on eGullet (found here http://forums.egullet.org/topic/145382-sous-vide-recipes-techniques-equipment-part-4/#entry1555277). I see it starts

with a steak at 41F and then gives bath temperature and time needed to

cook to reach approx. 130F.

For one, how do I check that the steak is at 41F. I use a thermometer

like the thermapen and check the raw steak's core temperature by

putting it in it right? Or can I/am I supposed to use an infared surface

thermometer?

I also understand that if I start with a steak that is 51F and I want

it to be at a core temperature of 140F then I still use the same exact

cook times and obviously adjust the waterbath temperature. Now, what if I

start with a steak that is 51F or higher (room temperature) and still

want it to be at a core temperature of 130F. The cook time is decreased,

correct? But, how do I figure out the perfect cook time? A math

equation?

I hate math. Instead of that, can I just let it cook for the same

length of time as if it started at 41F? It can't overcook right? The

only problem with letting it sit at that temperature longer would be

that it "dries out" a little or somehow negatively affects the meat? In

sous vide you want to cook something in the waterbath for as short as

you need to to achieve the desired core temperature and safety

precautions right? Letting the meat sit at core temperature of 130F for

longer because it started higher than 41F just means it is slightly

pasteurizing?

Or is there added flavor/tenderness benefits of letting it sit in the bath for longer? OR, I guess it just depends on the cut of meat (ny strip compared to duck breast compared to a rack of lamb).

I posted a similar/in some ways identical post on the eGullet yesterday but no one has answered and I'm hoping to find an answer to these questions somewhere. Thank you

Brendan_Lee_56950

With all sous vide cooking you are dealing with the core temperature so if you were to use a thermometer to check the meat you would try and get to the center of the protein. If you watch the videos on the site they use a thin almost hypodermic type probe that will cause minimal damage to the meat when inserting. This probe could also be put directly through the sealed plastic and a layer of foam tape and left in the bath while it cooks so you know the temperature at the core at all times.

As for the cook times, your best bet is to download the polyscience sous vide toolbox app. It will allow you to punch in the dimensions of your product, starting temp, bath temp, and it will calculate how long it should take to get the core up to temp and how long pasteurization would take if you wanted to do that as well.

There is no general rule for how long something will take to warm to a particular temp because size, shape, and starting temperature will all have an impact on the time to cook.

prince_of_porcelain

@Robert - The time aspect isn't nearly as critical with sous vide as other cooking methods. The effect of time depends on the cut of meat that you are preparing. In general tender cuts need less time (I'll say 45 minutes - 4 hours though that's probably a generalization) whereas tougher cuts (see short rib lesson in the sous vide class) can benefit from extended cook times (24-72 hours) - well beyond what's needed to reach core temp. The texture of a filet, for example, could suffer from an overly long cook, but a 15 minute extension probably won't be noticeable. The thickness of the portion will also greatly affect the time needed to reach core temp. In theory, starting temp will have an effect, but I imagine it's quite small. Much of the time is required to overcome the last couple degrees of difference between the product and bath temperature, so a 10 degree start temp difference should be overcome fairly quickly.

robert.c.brown15

Thank you so much for your answers! In terms of figuring out the core temp. before putting it in the bath, a thermapen probably isn't best in terms of puncturing the meat and introducing surface bacteria to the inside, right? It seems the core temperature before putting it in the bath is important, but doesn't need to be measured so exactly.

Can anyone direct me to NathanM charts for frozen to core temperature? Either Modernist Cuisine book pages or online charts? If I know those times that might be most ideal as when I get home from work I can throw two frozen steaks (in separate bags of course) into the waterbath and not spend the energy I otherwise would have thawing and cooking them as best I could.

Thanks again!

Brendan_Lee_56950

I don't know of any frozen to core time charts. I don't think they exist in the MC books nor have I seen them online. Not to say you can't do it but it's going to be more trial and error than math since the temperatures of freezers are all different.

prince_of_porcelain

Personally, on a steak, I'd add ~10 minutes to the time you'd use to cook from room temp and call it good. Check it after the first 10 minutes, if it's not frozen any more, you should be good to go. I don't usually cook from frozen, but I know many others here do. They probably have better advice, but that's how I'd go about it.

robert.c.brown15

Douglas Baldwin has charts frozen to pasteurization. I was just wondering if there were any that weren't to pasteurization as those cook times get long.

davidattala

While the Modernist Cuisine charts don't have anything where proteins start from frozen, they do have a separate set of times that are tacked on to the cook time of a given protein for pasteurizing. It might not be a bad idea to work backwards. Ie: If Baldwin says a given steak takes, say 2 hours to pasteurize from frozen AND MC says it requires 30 additional minutes to pasteurize said protein after hitting the desired internal temp., I would think you could get pretty close by simple subtraction.

DiggingDogFarm_65362

Baldwin has a chart of approximate times from frozen to 0.5°C less than the water bath's temperature.

HTH

~Martin

robert.c.brown15

@DiggingDogFarm I have seen that chart. I just read that Baldwin's charts run on the long side compared to NathanM's charts so I was wondering if NathanM had a similar chart.

You guys have been really helpful.

In terms of actual sous vide cooking, if a steak take 55 minutes at 130F, I don't start the clock until the waterbath says 130F, right? If I put a frozen steak in a bath that is 130F, the temperature will drop. Then once the temperature recovers to 130F that is when I start the timer. Is that right or do I just start the timer immediately, assuming the immersion circulator can recover the temperature within a reasonable amount of time (few minutes?).

Brendan_Lee_56950

Start the timer as soon as it goes in.

Chris_Young_80640

NathanM never did frozen charts for MC. Although there were attempts. The reason we skipped them was that, in the end, simulating the moving phase change boundary condition is an extremely difficult modeling exercise, and IIRC we never built a satisfactory model and could not find anyone else who had either.

robert.c.brown15

@Chris, can I trust baldwin's chart?

And thanks for the heads up about starting the timer when the food goes in. Why don't you wait for the water temperature to come back up though? Were all the times created with the expectation that it may take a few minutes for the water temperature to rise back up?

Brendan_Lee_56950

That's part of the cooking process, just like when you throw frozen peas into the pot of boiling water, it'll drop but rebound quickly. The exception is if you're not using a strong circulator or something like a beer cooler method where there is no possibility for the water to rebound.

robert.c.brown15

@Brendan_Lee, I wanted to check one last thing. Would a thermapen do too much damage to the raw meat if I use it to check the beginning core temperature? Should I just take whatever I'm cooking sous vide out of the refrigerator for 30 to 60 minutes and then put it in the bath and assume the core temperature is high enough that I can more or less follow the chart times. Do you check the core temperature of everything before you put it in the bath? And I'm talking about a 1 to 2 inch thick steak or something comparable to that, not a massive piece of meat that would obviously need to sit outside a refrigerator for a few hours.

Thank you! I'm running out of questions which is great. Definitely feeling more and more comfortable with all of this.

Johan_Edstrom_5586

I think you are missing a little bit one of the benefits of cooking proteins this way, once you have

hit core you can keep it there for a pretty good while. That is why you'll see time ranges as in

minimum -> maximum, maximum being where the texture starts changing in often "iffy" ways.

I cook most things from frozen, I also tend to cook bigger pieces, they are easier to plate and

are even more forgiving than say a steak.

For core temp in fish/lobster/sensitive proteins, I'd shove a thermocouple in the bag, if

you look at the store stuff you'll see nice thermometers there that are perfect for that use.

Brendan_Lee_56950

@robert I don't check the core temp really anytime. As Johan mentioned, one of the nice things about this style of cooking is to be able to throw it in and walk away for a portion of time to do other things. I don't really see anything wrong with using the thermapen but I would only check it once to avoid poking it a bunch of times and risking introducing bacteria to the inside of the protein.

One thing to consider is that leaving out a protein for 30-60 minutes to "come up to room temp" doesn't actually do that. I believe Kenji from serious eats did an experiment and the temperature difference after that amount of time was really negligible. The only starting temp scenario I really add extra time for is if it is starting from frozen. I sometimes buy pork chops in bulk, season them (sans salt) and cryovac so I can just throw them in directly from the freezer. When I do that I typically add about 30-45 minutes to the cook time.

robert.c.brown15

@Johan_Edstrom, when you cook from frozen, do you just throw it in the waterbath and add an hour or so depending on the product to make up for thawing time in the bath? I guess since I am not vacuum sealing it, after a time that I think may be long enough I could check the core temperature and if it is still too low just let it go back in the bath for whatever I think would be long enough. Is that ok/standard practice? I guess Dr. Baldwin's charts are very helpful for all of this too.

And is there a point where if the temperature drops by too much because say I add one big piece of frozen meat or two frozen strip steaks that he recovery time is too slow that it could create a safety problem. Or do I just add additional amount of cooking time to compensate? I hope to be purchasing an Anova Sous Vide circulator soon so I won't be using a beer cooler, hot water, and a thermometer, but I also won't be using a 1k professional immersion circulator.

Thanks for the help!

Brendan_Lee_56950

Well if you are using the beer cooler method then yes it'll drop more and more with the food that is added. I personally wouldn't recommend cooking from frozen in the beer cooler method but as you'll find when you get a circulator, the temperature doesn't fluctuate much even when you're throwing in a frozen hunk of meat.

As an example, I like to cook my higher temp products first and I have to throw in probably 3-4 cups of ice to bring down the temperature 10-15C to do other cooks. So if you are throwing in a frozen strip steak the temperature fluctuation isn't going to be huge in a heated bath.