1176 replies to this topic

[gfweb]

Why is vacuum needed? I know that sous vide means under vacuum, but why must one remove air rigorously to cook in plastic for 45 minutes?

[Ruth]

Simply because the bag will float if it contains air and the ingredients will not cook properly.
When cooking vegetables sous vide I always insert a small bag of pebbles into the main bag to prevent floating.

[DouglasBaldwin]

Guy MovingOn: When cooking meat, there really isn't any reason to go higher than 80C (175F). Back in the day I did a double-blind taste test between brined (7% NaCl soln for 48 hr) pork shoulder at 80C (175F) for 10 hours and at 70C (160F) for 24 hours: no one was able to tell the difference.

Now, cooking vegetables at 80C (175F) may pose some problems. With (non-starchy) vegetables it is all about dissolving enough of the cementing material that holds the cells together to make them easy to bite. [The literature refers to this as the beta-eliminative degradation (or depolymerization) of pectic polysaccharides.] I usually dissolving these pectic substances at 85C (185F) --- others cook their vegetables at 83C (182F). You can cook starchy vegetables though, since most starches gelatinize by 80C (175F) --- I usually cook them for about twice as long at 80C (175F) as I would have boiled them.

[MartinH]

Its interesting that there's been almost no discussion through the whole thread on vegetables, pulses and grains. (Though upthread #3125 Dec 21 Douglas mentioned he was planning experiments on starch cooking.) There seem to be no vegetarian SVers. Anyhow, is this near-silence a tacit recognition that the SV method has no real advantages when it comes to plant-eating? I am not convinced that that the extra chore involved in bagging is worth it. Compared to the major effects of small temperature differences in cooking an egg, thanks to its several proteins, likewise also with meat and fish, temperature precision seems to be much less critical for carbohydrates.

[MartinH]

Why is vacuum needed? I know that sous vide means under vacuum, but why must one remove air rigorously to cook in plastic for 45 minutes?

Sous vide is bit of a misnomer since a rigorous vacuum is not generally required. All that's needed is to squeeze out enough air so the bag doesn't float and there isn't a wide layer of air insulating the food from the water. Also, if you freeze it afterwards, the food avoids freezer burn. Another possible reason is to prevent the food in the bag from getting unwanted tastes from oxidization, though this may be moot because in practice with home vac sealers there's probably going to be some oxygen left in the bag.

Instead of sous vide, the technique should be called something like "Low Temperature Precision Cooking" - but a mouthful like LTPC isn't going to catch on.

[Guy MovingOn]

Guy MovingOn: When cooking meat, there really isn't any reason to go higher than 80C (175F). Back in the day I did a double-blind taste test between brined (7% NaCl soln for 48 hr) pork shoulder at 80C (175F) for 10 hours and at 70C (160F) for 24 hours: no one was able to tell the difference.

Now, cooking vegetables at 80C (175F) may pose some problems. With (non-starchy) vegetables it is all about dissolving enough of the cementing material that holds the cells together to make them easy to bite. [The literature refers to this as the beta-eliminative degradation (or depolymerization) of pectic polysaccharides.] I usually dissolving these pectic substances at 85C (185F) --- others cook their vegetables at 83C (182F). You can cook starchy vegetables though, since most starches gelatinize by 80C (175F) --- I usually cook them for about twice as long at 80C (175F) as I would have boiled them.

Thank you Douglas! Now I'm even happier with my waterbath! I was just a bit worried as I saw many confit and vegetable recipes requiring 83+C temperatures, but thankfully my confit tasted amazing at 80C! :)

I wanted to ask you two questions. I cooked some chicken breasts last night. In your guide you suggest a brine solution of 5%. I believe in some of the recipes in Under Pressure, Thomas Keller uses a 10% solution, and sometimes 10% sugar as well. Would there be a noted difference between the two? Furthermore how would the duration of time in the brine affect the meat?


I was interested to see that poultry and eggs can be pasteurised at 57.5C, if held at that temperature for a long enough time. Is this the absolute lowest temperature at which pasteurisation can be achieved?

I thought I was going to be short for time last night, so cooked the chicken at 63.5C rather than the 60C I had tried before, in fact I ended up with enough time to have cooked at 60C. I definitely noticed a drier and harder texture. So I would be really interested to try 57.5C :)

Once again thanks for all your guys help!

[Guy MovingOn]

I have a very small joint of smoked gammon (about enough for 2 people). Can anyone suggest how to cook it?

Brine? And if so, other flavourings in the brine?

Temperature? And time once the core has come up to that temperature?

Many thanks! :)

[PedroG]

I'm currently watching Heston Blumenthal's Feast videos.

On recreating a Roman feast, he vacuum packs a whole pig, and cooks it in a hot tub/jacuzzi at 60C for 24 hours.

You will need to skip about 25 mins in. :)

Here's the sous vide segment for those living outside of England (the content is blocked on youtube)

trojan hog

Pretty insane. The best part is when he serves it with the sausage at the end.

Hi Therippa,
thanks for the link. Really insane!
But I wondered if I could heat a bath-tub with the FreshMealsMagic, so I filled it with 130L of hot tap water (as opposed to the 13L in the polycarbonate container that comes with the FMM) and started heating with the FMM and then ran an auto-tuning. And in fact, it works! Heat loss is -0.117°C/min, and with full heating power, temperature rises 0.111°C/min. My FMM is 220V/2000W; with a 110V/1500W FMM heating will be slower, but it should hold the temperature. Temperature uniformity in the bath was within ±0.5°C.
So if someone plans to do a suckling pig SV, FMM in bath-tub might do.
Pedro

[Guy MovingOn]

Hahahahaha!!! Omg you are insane! If you have any means to vacuum pack a whole animal, pleeeaaase try this! :D:D

[MartinH]

I have a very small joint of smoked gammon (about enough for 2 people). Can anyone suggest how to cook it?

Brine? And if so, other flavourings in the brine?

Gammon is, I think, a term used for a cut of ham so it has already been brined by the manufacturer. Another brining would seem to be unneeded, and might well make it too salty. (The word gammon is not used in North America.)

[therippa]

Pedro,

You should do the pig for your next dinner party just so you can say you did it

-Jason

[PedroG]

Hahahahaha!!! Omg you are insane! If you have any means to vacuum pack a whole animal, pleeeaaase try this! :D:D

There are large plastic bags for storing and compressing e.g. textiles, which have a valve and can be evacuated with a vacuum-cleaner. A small suckling pig should fit.
But I am definitely NOT going to cook a Trojan Hog!

[therippa]

I imagine the suckling pigs get shipped vacuum sealed anyway...most sub-primal cuts are shipped that way to stores. You could just ask them to not take it out of the bag.

[DouglasBaldwin]

...
I wanted to ask you two questions. I cooked some chicken breasts last night. In your guide you suggest a brine solution of 5%. I believe in some of the recipes in Under Pressure, Thomas Keller uses a 10% solution, and sometimes 10% sugar as well. Would there be a noted difference between the two? Furthermore how would the duration of time in the brine affect the meat?

I was interested to see that poultry and eggs can be pasteurised at 57.5C, if held at that temperature for a long enough time. Is this the absolute lowest temperature at which pasteurisation can be achieved?

I thought I was going to be short for time last night, so cooked the chicken at 63.5C rather than the 60C I had tried before, in fact I ended up with enough time to have cooked at 60C. I definitely noticed a drier and harder texture. So I would be really interested to try 57.5C :)

Once again thanks for all your guys help!

You can pasteurize poultry at 54.5C (130F) and 57.5C (135F), it just takes longer:

     Reducing Listeria by 1 million to 1 in poultry
   130F (54.5C) water bath ;   135F (57.5C) water bath 
   mm; hours; inches; hours;   mm; hours; inches; hours
    5;   5.6;   0.25;   5.6;    5;   1.7;   0.25;   1.7
   10;   5.7;   0.5 ;   5.8;   10;   1.8;   0.5 ;   1.8
   15;   5.9;   0.75;   5.9;   15;   1.9;   0.75;   2.0
   20;   6.0;   1   ;   6.2;   20;   2.1;   1   ;   2.4
   25;   6.2;   1.25;   6.7;   25;   2.3;   1.25;   2.8
   30;   6.6;   1.5 ;   7.2;   30;   2.6;   1.5 ;   3.2
   35;   6.9;   1.75;   7.7;   35;   3.0;   1.75;   3.8
   40;   7.3;   2   ;   8.3;   40;   3.4;   2   ;   4.4
   45;   7.7;   2.25;   9.0;   45;   3.8;   2.25;   5.1
   50;   8.2;   2.5 ;   9.8;   50;   4.3;   2.5 ;   5.8

Here I used D_60C^5.66C = 5.94 minutes for Listeria monocytogenes, a thermal diffusivity of 1.08 10^-7 m²/s for poultry, and assumed the slowest heating shape (an infinite slab) at each thickness.

Brining is always an interesting subject. For the last couple of years, I've only been brining meat that I cook well done: pork shoulder for pulled pork; duck and turkey legs for confits; brisket for corned beef; etc. I brine meat I'm going to cook well done to compensate for some of the water that is lost when the muscle fibers shrink longitudinally and squeeze out the water held between its thick (myosin) and thin (actin) muscle fibers. At least for pork, a brine of 7--10% NaCl gives the highest increase in water.

But there is another reason to brine: coagulate the albumin before it can coagulate on the surface. This is often called salting out the proteins. This is why Mr Keller sometimes brines fish in a 10% brine for a short time.

Edit: Clarified.

Edited by DouglasBaldwin, 26 February 2010 - 10:25 AM.

[Guy MovingOn]

I tried bidding on the Lava V333, but even at £170 the Reserve wasnt met, and I didnt want to pay the £295 Buy It Now price.
I've therefore just purchase the Foodsaver V2860 for £108.08 including delivery. Will report back upon using it! :D

[Guy MovingOn]

...
I wanted to ask you two questions. I cooked some chicken breasts last night. In your guide you suggest a brine solution of 5%. I believe in some of the recipes in Under Pressure, Thomas Keller uses a 10% solution, and sometimes 10% sugar as well. Would there be a noted difference between the two? Furthermore how would the duration of time in the brine affect the meat?

I was interested to see that poultry and eggs can be pasteurised at 57.5C, if held at that temperature for a long enough time. Is this the absolute lowest temperature at which pasteurisation can be achieved?

I thought I was going to be short for time last night, so cooked the chicken at 63.5C rather than the 60C I had tried before, in fact I ended up with enough time to have cooked at 60C. I definitely noticed a drier and harder texture. So I would be really interested to try 57.5C :)

Once again thanks for all your guys help!

You can pasteurize poultry at 54.5C (130F) and 57.5C (135F), it just takes longer:

     Reducing Listeria by 1 million to 1 in poultry
   130F (54.5C) water bath ;   135F (57.5C) water bath 
   mm; hours; inches; hours;   mm; hours; inches; hours
    5;   5.6;   0.25;   5.6;    5;   1.7;   0.25;   1.7
   10;   5.7;   0.5 ;   5.8;   10;   1.8;   0.5 ;   1.8
   15;   5.9;   0.75;   5.9;   15;   1.9;   0.75;   2.0
   20;   6.0;   1   ;   6.2;   20;   2.1;   1   ;   2.4
   25;   6.2;   1.25;   6.7;   25;   2.3;   1.25;   2.8
   30;   6.6;   1.5 ;   7.2;   30;   2.6;   1.5 ;   3.2
   35;   6.9;   1.75;   7.7;   35;   3.0;   1.75;   3.8
   40;   7.3;   2   ;   8.3;   40;   3.4;   2   ;   4.4
   45;   7.7;   2.25;   9.0;   45;   3.8;   2.25;   5.1
   50;   8.2;   2.5 ;   9.8;   50;   4.3;   2.5 ;   5.8

Here I used D_60C^5.66C = 5.94 minutes for Listeria monocytogenes, a thermal diffusivity of 1.08 10^-7 m²/s for poultry, and assumed the slowest heating shape (an infinite slab) at each thickness.

Brining is always an interesting subject. For the last couple of years, I've only been brining meat that I cook well done: pork shoulder for pulled pork; duck and turkey legs for confits; brisket for corned beef; etc. I brine meat I'm going to cook well done to compensate for some of the water that is lost when the muscle fibers shrink longitudinally and squeeze out the water held between its thick (myosin) and thin (actin) muscle fibers. At least for pork, a brine of 7--10% NaCl gives the highest increase in water.

But there is another reason to brine: coagulate the albumin before it can coagulate on the surface. This is often called salting out the proteins. This is why Mr Keller sometimes brines fish in a 10% brine for a short time.

Edit: Clarified.

Wow thank you, I think next time I will try cooking chicken breasts at around 55C just as an experiment. Not sure if my girlfriend will like it, but I can just stick hers onto the griddle if she complains! :)

Thank you for the brining information. I didn't realise duck legs can be brined before confit, I always thought they had a sort of salty dry rub instead.

I had read, either in this thread, or in your guide, about brining fish before cooking to prevent albumen coagulating on the surface.
So I guess it doesn't matter too much? Anything between 5-10% will provide a juicier result than if you had done nothing?

[Guy MovingOn]

I have a question about measuring the thickness from an infinite slab.
.......__
....../../|
...../../.|
..../../..|y
.../../...|
../../..../
./../..../
/__/..../z
|..|.../
|..|../
|..|./
|__|/
x

If the slab above is our piece of meat. I presume that being an infinite slab, it is infinite along z. To measure thickness according to the tables, do we take x or y to be the thickness? In the case of a chicken breast, I guess the slab pictures above would be like a chicken breast on its side?


hmm my diagram doesnt work... using some full stops to space it out

Edited by Guy MovingOn, 26 February 2010 - 11:41 AM.

[PedroG]

It is "infinite" along y and z, the relevant thickness is the smallest dimension x.
See also http://forums.egulle...ost__p__1717666

Thickness refers to twice the shortest distance to the least accessible part of the food, "slab" refers to something between an infinite slab and 2 x 3 x 5 block, "cylinder" refers to something between an infinite cylinder and a 1 x 1 x 5 block, and "sphere" refers to something between a cube and a sphere.

How to measure thickness:

[DouglasBaldwin]

PedroG: That is a wonderfully illustrative picture.

Guy MovingOn: When doing confits you have to ask yourself if you are doing it for taste or for preservation. The recipe in my guide is confit-for-taste and uses a lower concentration of salt. Confit-for-preservation uses a larger amount of salt (or salt and sugar) to reduce the water activity* of the meat to below 0.91. This can be done either by packing the meat in salt or using a very concentrated brine---depending on the thickness of the meat, it may take several days (or weeks) to reduce the water activity enough. (See the charcuterie index for more details.) I find confit-for-preservation to be too salty for my palate and just freeze the confit-for-taste I make to keep it safe. (See the food safety section of my guide for more details.)

* Water activity (a_w) is the vapor pressure of the food divided by the vapor pressure of water at that temperature. A long time ago, food scientists noticed that bacteria stop growing below certainly water activity levels; for instance, C. botulinum cannot grow if a_w < 0.94 and Salmonella spp. for a_w < 0.92.

[DouglasBaldwin]

...I will try cooking chicken breasts at around 55C just as an experiment. Not sure if my girlfriend will like it, but I can just stick hers onto the griddle if she complains! :)...

I'll be surprised if either of you like it. At 55C (131F), the enzyme collagenase will break down a significant amount of collagen in the 6 hours it takes to pasteurize it. You may enjoy chicken breasts at 57.5C (135F) since it only needs 2.5--3 hours. [I remember liking it at 57.5C (135F) when I tried them a couple years ago. My family just couldn't get used to its appearance. Until most people accept that you can't judge safety by appearance, many people will feel uncomfortable eating medium-rare poultry :-(.]

[PedroG]

Douglas,
how did you vacuum-seal your chicken breasts when comparing 55°C/6hrs to 57.5°C/2.5-3hrs? Did you use your chamber machine? How much vacuum? Could the mushy feeling have been caused by high vacuum? See http://www.cookingis...e-of-your-meat/
With clamp-type vacuum machines too high vacuum does not occur, see also http://sousvide.wiki...achine_produces
Pedro

[DouglasBaldwin]

PedroG,
I haven't tried 55C/6hrs, I was stating a hypothesis; hopefully Guy MovingOn will let me know if my hypothesis was correct. I haven't had chicken at 57.5C/3hrs for several years; I remember enjoying it but my family being turned off by its appearance. While I almost always use my chamber vacuum sealer, I usually seal the breasts while they are frozen --- since they are frozen, even pulling the highest vacuum doesn't damage their texture.

[blackp]

Pedro,

I have cooked chicken breasts @55C and the result was very good. I was cooking some beef ribs @55C for 48 hours (deliberately low to maximise the "rare" appearance) for a presentation a couple of weeks ago and decided at the (relative) last minute to give the audience a sample of chicken breast as well. I had a couple of fresh free range breasts in the fridge which were to be that night's dinner. I bagged them with a sprinkle of white truffle salt and white pepper using my normal SV pressure (97%) in my chamber machine.

I cannot be sure of the exact vacuum which is pulled at that setting, but I find it is sufficient to extract enough air so that the bags easily sink. Interestingly freezing using that vacuum level tends to allow ice crystals to form in time whereas holding 99% for a few seconds does not. (Note that my machine only has a 2 digit readout so 99% really equals the maximum it can pull. Once you pull 99% you get an option to hold that pressure for a programmed number of seconds whereas at lower pressures there is no hold option).

I found a digital pressure gauge which would let me know the exact vacuum pulled but at >$700 I can't quite see getting value from it.

Anyhow I cooked the breasts for about 4.5 hours. The texture was a little softer than chicken from the same source cooked @58C for 2 hours, but it was still "al-dente" and not at all mushy. As for colour it was slightly pinker than the 58C breast, but it was not at all undercooked.

The neophyte tasters all thought it was brilliant!

Cheers,

Peter.

[e_monster]

...I will try cooking chicken breasts at around 55C just as an experiment. Not sure if my girlfriend will like it, but I can just stick hers onto the griddle if she complains! :)...

I'll be surprised if either of you like it. At 55C (131F), the enzyme collagenase will break down a significant amount of collagen in the 6 hours it takes to pasteurize it. You may enjoy chicken breasts at 57.5C (135F) since it only needs 2.5--3 hours. [I remember liking it at 57.5C (135F) when I tried them a couple years ago. My family just couldn't get used to its appearance. Until most people accept that you can't judge safety by appearance, many people will feel uncomfortable eating medium-rare poultry :-(.]

For what it's worth, in my experience, this is an area where palates seem to have very different responses and one hust has to try at a variety of temps and find out what you like. I have tried chicken breasts at a lot from temperatures from 133F long enough to pasteurize to 160F for 30 minutes. My personal favorite is somewhere in the 138F to 142F range. I personally found the texture at 133F and 135F not quite as pleasing as that around 140F (and to let you know where I am coming from, I like my steak down in the region from 125F to 129F). I like them at the lower temps just not as much.

When I have served chicken in the 130s, there have been a few people that were very lukewarm to it but I haven't had that response to it at 140 or so.

At a given temperature, the texture seems to vary a lot more with chicken from source to source than it does with beef, pork and fish. I have no idea why that is, but that is what I have found anyway.

I also am convinced that a couple of hours in a 5% brine does wonders for chicken cooked in any fashion.

[dougal]

... I bagged them ... using my normal SV pressure (97%) in my chamber machine.

I cannot be sure of the exact vacuum which is pulled at that setting, but I find it is sufficient to extract enough air so that the bags easily sink. ...

Ummm.

A question.

Yes we know that bags floating horizontally is not good.
And yes, its good to get as much air out as you can. Though I'm sure that the last small bubbles aren't critical.

But isn't it a worthwhile idea (at least for those without such chamber machines) to routinely use solid glass gems/nuggets/pebbles/cubes to add a little weight to the bottom of all bags to prevent any bag ever floating horizontally?

These items are food-safe, non-tainting, cheap, re-usable, freezable, easily washable, can be blasted in the oven for as long as you like to sterilise them and then stored in a sealed sterilised jamjar.

Since they need to be found and removed before service, maybe unusual colours (like blue) are a good thing!
Its probably also worthwhile choosing those with a simple shape and a shiny-smooth surface for better sanitisation.

Examples:
Clear cubes in the UK http://www.carnmeal....s-1-kilo-approx
Blue pebbles in the UK http://www.dotcomgif...gems-in-bag400g
Blue cubes in the USA http://www.save-on-c...bluecubes1.html
or Blue 'vase gems' http://www.save-on-c...ybluvasgem.html
But if you have a local floristry supplier, they should be cheaper than mailing ballast.

Edited by dougal, 27 February 2010 - 09:06 AM.

[PedroG]

Dougal,
why didn't I have this good idea before you??
Pedro

[slkinsey]

Whenever I'm cooking something where it's impossible to extract sufficient air from the bag to prevent floating (e.g., cauliflower), I simply leave a "tail" on the bottom of the bag and use a heavy binder clip to attach a heavy weight. Down it goes and down it stays. And I don't have to worry about having a foreign object in the bag.

[Guy MovingOn]

I'm going to try chicken breasts cooked at 57.5C first. If I like them, then I will try chicken breasts at 55C. To give you an idea, I like my steak very rare :)
I bagged them with some sea salt, black pepper, garlic powder, thyme, lemon juice, butter, and olive oil. They measure approximately 35mm in thickness, however I will cook to pasteurisation as if they were 40mm, which is 3hr18min, just as a margin of safety, and in case the bath goes slightly below 57.5C. I'm also sure that they were above 4C when I put them in the bath, so they would take less time to come up to temperature anyway.

Will report later this afternoon when I've had them for lunch!

[jk1002]

I had boneless skinless chicken few times, last night I brined for 2 hours in 10% it did not lost a single drop of juice in the bag. In fact the meat was sticking to the plastic - I had nothing in the bag except the chicken breast - no fat no spices. I topped them later with a rub and some kumquats and stuck them under the broiler based on a recipe from JG Vongerichten.

Thing is, the texture reminds me too much of Boars head lunch meat. I now sort of have the feeling that they meat glue chicken breast together, then SV it for hours.

I have tried few times to incorporate SVed chicken into normal recipes but always come back to the lunch meat like texture. I find if I pan sear it afterwards, the browned part gets too hard and stringy in contrast to the rest of the meat.

I think I will try 2 things next: gently brown the skinless breast in a pan before SVing as well as take one with bone and skin and finish it off under the broiler.

Question I have is, after browning the breast do I need to chill if I stick it into the water bath right away? In the Polyscience youtube video for tenderloin he is doing that but then he is using a true vacuum machine which lowers the boiling point which I do not have. I use ziploc.

Edited by jk1002, 28 February 2010 - 09:06 AM.

[Guy MovingOn]

I'm going to try chicken breasts cooked at 57.5C first. If I like them, then I will try chicken breasts at 55C. To give you an idea, I like my steak very rare :)
I bagged them with some sea salt, black pepper, garlic powder, thyme, lemon juice, butter, and olive oil. They measure approximately 35mm in thickness, however I will cook to pasteurisation as if they were 40mm, which is 3hr18min, just as a margin of safety, and in case the bath goes slightly below 57.5C. I'm also sure that they were above 4C when I put them in the bath, so they would take less time to come up to temperature anyway.

Will report later this afternoon when I've had them for lunch!

I just ate the chicken. In total the chicken was in the bath for around 3:40 as I was making some soup as well, so it was definitely past pasteurisation.
The chicken was delicious! I really loved the texture. It wasn't at all soggy or flimsy or sponge-like. Perfect structural integrity, nice soft texture, wonderfully moist. It wasn't even that pink at all.
The skin was very soft, but not unpleasantly so. My girlfriend is quite fussy when it comes to food, but she loved this chicken and said it is the best so far, having also tried chicken at 63.5C and 60C. She wasn't a fan of the soft skin though. I was thinking perhaps I could place it skin side down in an extremely hot pan, but I wouldn't want to cook the meat any further. Perhaps I will try with my blowtorch next time. I thickened the cooking juices with some cornflour (probably could have found a better thickening agent in my TexturePro kit, but I'm lame at molecular gastronomy/cooking), and drizzled some over :) It made a delicious sauce!

Having tried this temperature, I'm not sure if I would prefer it at a lower temperature. I will, however, try it at 55C for experiment's sake.

Furthermore, I have also been rather retarded with my brining, and been doing 1% instead of 10%! Haha, no wonder I wasn't noticing much difference!

I had wonderful results with these chicken breasts, and they are just standard supermarket chicken breasts. I am sure they would be even nicer if I bought some of the organic or free range chicken breasts :)

Again, terrible photography with my iPhone 3G, and horrible presentation skills, but in case you are interested:







Happy with this afternoon's results, I'm going to make a sous vide version of Chinese drunken chicken.