Sous Vide: Recipes, Techniques & Equipment (Part 4)

[Chris Hennes]

HOST'S NOTE: The recent discussion on cooling rates has been split into its own topic, which may be found here.

[e_monster]

Answering my own question about tri-tip. I cooked a 2.5 lb tri-tip at 135F for 22 hours bagged with a marinade of olive oil, soy sauce, a tiny amount of liquid smoke, sugar, a balsamic vinegar. After removing from the bath, I seared it for those lovely maillard reaction flavors at very high temp for 30 seconds per side.

The result was extremely tender but perhaps slightly 'softer' than I'd like. My wife pointed out that the tenderness was perfect the next day for cold steak sandwiches. Next time, I will try it for 12 hours to see if the meat will be tender but a bit firmer. The result was judged very good by the people that shared the meal with us but I personally think that the result would be much better with different cooking parameters.

The meat was a very good but not premium quality steak. Next time, I will also use a more premium source.

(Question: anyone in the Bay Area know of somewhere where good Wagyu beef can be purchased?)

Here are some pics:

Fresh out of the bag:

After searing:

Sliced:

[e_monster]

What is the lowest temperature that one can safely use for a 24 to 48 hour cook when cooking beef?

[nathanm]

There are two ways to answer - the official FDA answer, and the best available scientific information. They are different.

For an "intact beef steak" the FDA requires that the outside be seared to 145F. There is NO REQURIEMENT on internal temperature whatsoever, and no requirement on the cooking temperture. There is also a general FDA rule that food should not spend more than 4 hours between 40F and 130F.

So, if you want to go by the letter of the ruling, you can cook a beef steak at any temperature you want so long as the exterior is seared, but you can't cook it for more than 4 hours if the temp is below 130F/54.4C.

For a beef roast, the minimum FDA temperature is 130F/54.4C. You might ask "how is a roast different from a steak?". Most steaks are cut from muscles that could be roasts. The answer is that there is NO definition of the terms in the FDA Food Code. Steaks are given a special case because of tradition support for rare steaks and politics of the beef industry.

130F is also the lowest temperature the FDA recommends for effective food safe sterilization/pastereurization - and they give time-tempertaure tables fors this.

So, the FDA answer is that it is definitely OK to cook at 130F, if you cook for at least 90 minutes. For a beef steak there is no lowest temperature, but you can only cook below 130F for 4 hours.

Scientifically speaking the issue is quite different.

Intact muscle is sterile inside. If the outside is well seared before cooking in a clean, sealed sous vide bag, and very good hygiene is observed, then it is almost certainly safe to cook at lower than 130F.

How much lower is an interesting question.

There are numerous scientific papers documenting the killing of pathogens at various temperatures. The lowest temperatures commonly reported as being effective for killing Salmonella, Listeria, Camplyobacter and other common food pathogens is 120F/48.89C. A few papers suggest even lower temperatures for a few pathogens (E. coli, for example). The key point is that 120F is found in dozens of papers.

So, it is likely the case that 120F/49C is a safe temperature as long as you cook for long enough. The next question is how long?

Many people have the wrong intuition here - they say "how long can I cook it at that low temp". The real question is the OPPOSITE - what is the SHORTEST time that I can cook it and be safe? The longer you cook something the more likely you kill the pathogens.

The simplest approach to this is to extend the FDA food safety table. I won't repeat the whole table, but the last two temps are:

133F .... 56C .... 1.0 hours

131F .... 55C .... 1.5 hours (this is the lowest in the FDA table)

extrapolating mathematically from the same curve, we get

129F .... 54C .... 2.33 hours

127F .... 53C .... 3.5 hours

126F .... 52C .... 5.3 hours

124F .... 51C .... 8.0 hours

122F .... 50C .... 12.1 hours

120F .... 49C .... 18.4 hours

These numbers are rounded a bit for convienence.

Note that these figures are NOT a guarantee on my part that your food will be safe. That depends on many factors and you must be responsible for your own actions here. Below 130F is definitely below FDA recommendations.

However, my personal (and extensive) survey of the scientific literature suggests that beef brought to the temperatures above, and held there for at least the time in the table above, will likely render it just as safe as the FDA time-temperature tables. But again, this is not a guarantee!

Normally I like to sear meat after sous vide cooking. However when cooking at lower temperatures than 130F, I would sear first, as an added precaution.

Finally, note one more thing - the main reason to slow cook meat at low temperature is to keep the meat rare to medium rare, while at the same time making it tender through denaturing collagen into gelatin.

The lower the temp, the more rare it will be - however at some point the temperature will get so low that the collagen will be very slow at denaturing into gelatin. If you go too low it might be self defeating. Unfortunately it is not known what the minimum temperature is for collagen denaturing, so we don't know exactly how low is too low, you just have to experiment.

[nathanm]

There is an interesting thread (which originated as a discussion in this thread) on the safety aspects of cooking salmon mi-cuit. Since most people who cook salmon or other fish sous vide use low temperatures, I think it is an important topic for sous vide.

It can be found here.

Edited August 26, 2008 by nathanm (log)

[e_monster]

I have a question about safe reheating of food cooked sous-vide then subsequently re-portioned and frozen.

A month ago, I cooked a whole brisket sous-vide and knew that it was more than we would eat. So, I cut the brisket in half and served half. The other half was put in the fridge and then re-vacuum packed a couple of hours later.

To reheat, should I defrost in the refrigerator and then re-heat. Or, is it safe to put it straight into a 135 F bath and brought to temp.

I have no idea how long it would spend in the danger zone if put directly in the bath from the freezer.

[DouglasBaldwin]

There is no need to thaw before reheating --- you can always place the frozen food directly into the water bath.

In the future, I would highly recommend packaging large cuts of meat into portions for 2-3 people. Then, you will only need to open as many portions as you need. The problem with repackaging leftovers, is that the pasteurized meat can easily be contaminated by food pathogens and spoilage microorganisms. This will severely reduce the storage life of your sous vide prepared foods. It also means that you should re-pasteurize the leftovers before eating them.

On the other hand, food which is still in the vacuum pouches it was cooked in, do not need to be re-pasteurized and can even be eaten cold --- so long as they were stored for a time and temperature combination that prevented any spores from outgrowing and multiplying to dangerous levels (see my guide or post #1773 in this thread).

There is an interesting thread (which originated as a discussion in this thread) on the safety aspects of cooking salmon mi-cuit. Since most people who cook salmon or other fish sous vide use low temperatures, I think it is an important topic for sous vide.

I absolutely agree with Nathan. I think it is very important for practitioners of sous vide to understand all the food safety issues connected with the technique.

[Sher.eats]

Hi,

Some random questions....

1. For cuts of meat low in collagen (tenderloin?) is there a difference to SV at 65C compared to 95C? Both temp will overcook the meat but will the 95C be more mushy?

2. In meat, how is the water "stored", all as blood? When overcooking and the meat expels juice is that all cooked blood? Beef cooked below 54C shouldn't loose any "juice" right?

3. Can one "fix" or "retrograde" meat cells before cooking to "strengthen" meat cells?

3. What temp should foie gras be SV at? What is the structure of FG, fat inside cells or fat held by a "net" of cells?

Thanks everyone!

[slkinsey]

Some Random answers...

1. For cuts of meat low in collagen (tenderloin?) is there a difference to SV at 65C compared to 95C? Both temp will overcook the meat but will the 95C be more mushy?

The 65C meat will be cooked to a uniform medium-well. The 95C meat will be hammered through like braised meat. Whether one is more "mushy" than the other, or indeed whether one is "mushy" at all will depend on time-at-temperature.

2. In meat, how is the water "stored", all as blood? When overcooking and the meat expels juice is that all cooked blood? Beef cooked below 54C shouldn't loose any "juice" right?

This is really two separate questions. To answer the first one, there is no blood in beef. Beef is exsanguinated as part of the slaughtering process. To answer your second question, any time you heat meat to the point where it is "cooked" there will be some loss of liquid. 54C steaks definitely lose "juice" in the bag.

3. Can one "fix" or "retrograde" meat cells before cooking to "strengthen" meat cells?

No.

[Sher.eats]

Hi slkinsey, thanks for replying,

I thought (wrongly) 65C would yield completely grey and dry meat, I should have asked if there is a difference SVing at any temp above "fully cooked" (OTBE)?

The red coloured liquid expelled from meats when cooked lightly is not blood?

I'm quite confused at the doneness of meats: when the meat cells are heated beyond 53ish (not sure exactly) the protein denatures and changes shape, "squeezing" out the "juice?" stored inside (or between?) the cells. Is this in stages (maybe only 10% of "juice" will be expelled at 53C even after a long time) or is there an absolute temp (once above 53C it starts and the higher the faster, but if kept at 53C for a long time it will eventually all come out)? And then there's the change of colour from red to brown due to the myoglobin, there are also "stages": red pink light pink etc is this absolute or stages?....

haha very confused, thanks again!!!

[slkinsey]

I thought (wrongly) 65C would yield completely grey and dry meat, I should have asked if there is a difference SVing at any temp above "fully cooked" (OTBE)?

It depends on temperature but also on time at temperature. Think about it: If you put a chunk of stew beef in simmering water and take it out after 2 minutes, it's going to have a different texture from a piece that has been in the simmering water for 20 minutes... which will be different from a piece that has been in there for 2 hours.

The red coloured liquid expelled from meats when cooked lightly is not blood?

Right. It is not blood.

I'm quite confused at the doneness of meats: when the meat cells are heated beyond 53ish (not sure exactly) the protein denatures and changes shape, "squeezing" out the "juice?" stored inside (or between?) the cells. Is this in stages (maybe only 10% of "juice" will be expelled at 53C even after a long time) or is there an absolute temp (once above 53C it starts and the higher the faster, but if kept at 53C for a long time it will eventually all come out)? And then there's the change of colour from red to brown due to the myoglobin, there are also "stages": red pink light pink etc is this absolute or stages?....

Maybe you might want to ask this in another thread, as it isn't entirely topical for sous vide.

[jackal10]

Suggest you read McGee pp 148-154 for a full and clear explanation.

When you cook meat a number of processes happen each at different rates, and the rates are temperature dependent. NO temperatures are absolute, as for most natural processes there is a rate of reaction at any given temperature.

1. The fibers coagulate. This starts around 120C, and is mostly complete by 65C. The hotter the more tightly bound the proteins become.. The muscle cell becomes a coagulates protein core surrounded by fluid, inside a muscle fibre sheaf mostly of collagen. Some of the fluid is lost where the fiber sheaf ruptures in weak spots.

2. The collagen shrinks. Between 60 to 65C the collagen sheaf shrinks and eventually bursts, releasing the fluid.

3. At a rate dependent temperature, but quite fast above 70C the collagen dissolves into gelatin, and the meat falls apart into fibres.

4. Around 60C the myoglobin starts to turn from red to grey brown, although the myoglobin that has escaped with the meat juices may stay cooler and hence pink.

Also the inside of the meat does not heat up immediately, as meat is rather a poor conductor of heat, but can take several hours to get to temperature, depending on thickness and temperature difference. Often a steak is well cooked and grey brown on the outside, and less cooked and pink in the center.

So to answer your questions:

It depends how long you hold at the temperature which will (mostly) govern how much of the collagen coverts to gelatin. The hotter the meat the faster it converts, say say 4 hours at 65C will yield tender meat, 4 hours at 95C will give falling apart meat like overcooked stew.

Try it and see

The water is stored as fluid in the cells. Meat at 54C will lose some, but nowhere near as much as at 65C.

The red fluid is not blood. It is the intracellular fluid plus some myoglobin. Brillat Savarin called this fluid "osmazome", and described it as the soul of the meat.

[JohnV]

Pretty decent survey by the Wall Street Journal today on doing sous vide at home:

WSJ Sous Vide Article

Highlights include quotes and recipes from Nathan, a shout-out to this eGullet thread, and the big news that some consumer-targeted sous vide appliances will be released this fall, just in time for Thomas Keller's new cookbook.

Fresh Meals Solutions (who resell the Auber Instruments PID controller as "Sous Vide Magic") will be releasing the "eiPot" for $399, and it includes circulation and an internal probe sensor. Sur La Table will be selling immersion circulators starting at $1000. And there is also confirmation (as I linked to up-thread) that Viking is developing sous vide appliances that will be integrated into their product line.

The article also reports that Nathan's book is scheduled for late 2009. Says that equipment is being tested as part of that project. Is that just for review and testing, or is the plan also to develop new appliances as part of the project?

[nathanm]

No plans to make equipment - we are just working on a book! But we have tested, and will describe, a bunch of different kinds of sous vide equipment.

[nickrey]

I tried sous vide chicken breasts for the first time today.

Followed Douglas Baldwin's recommendation of brining in a 5% salt solution for an hour. Added salt and pepper to one side of the meat then sealed it in a bag with an ice cube worth of frozen chicken stock.

I cooked it at 60 degrees celsius for what actually turned out to be four hours (much more than minimum recommended time but it was to target temperature so it didn't really matter).

Saw a video on you-tube by David Myers who had a good idea on how to serve it.

I mixed some yoghurt with a ready made Bombay sandwich spread: a coriander and mint type pesto and spooned it on the plate in a leaf vein type pattern. Filled this in with flash fried baby spinach that had home-made lime pickle mixed through it.

Flash fried the chicken to brown it and sliced it into serving pieces.

Poured the contents of the bag into a saucepan, added another ice cube of chicken stock and reduced it to around a tablespoon worth of sauce which I drizzled over the chicken.

Also prepared some glazed baby carrots (with onion, garlic, sherry vinegar, honey, saffron, salt pepper).

The finished dish looked like this:

The meat was extremely moist and flavorful.

Edited September 1, 2008 by nickrey (log)

[DaleJ]

Assuming the circulation aspect is to ensure even distribution of heat, how serious is the compromise if one employed an "immersion heater" (without a circulating device)?

I can get one at a great price.

[e_monster]

You can use a cheap aquarium air pump (less than $10) to provide circulation. Search this topic for "aquarium" for more details. (The 'search topic' field is found towards the bottom of the page).

It should also be noted (for those without inexpensive access to an immersion heater) that there are many under $50 heat sources that when coupled with a $10 aquarium pump and a PID controller (around $100) make for an excellent sous-vide setup.

[dougal]

Assuming the circulation aspect is to ensure even distribution of heat, how serious is the compromise if one employed an "immersion heater" (without a circulating device)?

I can get one at a great price.

←

I think its worth making explicit the implication behind e_monster's reply.

The heat source isn't really any great problem (or expense).

Controlling the heat of the bath, (super-accurately by traditional cooking standards, and over a rather long period), is the major technical challenge.

Hence the requirement for some form of proportional controller.

Rather than a so-called "bang-bang" (simple on/off switching) thermostat.

So its not the immersion heater itself that would be the problem, but its thermostat - which you could likely bypass by setting it to maximum, always on, so that a more sophisticated controller was able to take charge.

Stirring the bath (even with the bubbles from an aquarium pump) will help to maintain the whole bath (rather than just the neighbourhood of the temperature probe) at the desired temperature.

It really shouldn't be a problem (at least once the bath is stabilised at temperature), but guarding an immersion heater element from direct contact with plastic vac-pac bags might be no bad thing.

[lennyk]

Did some short ribs in a bulgogi marinade for both 24 hours and 36 at 140f

stir fried them in a hot wok to sear them afterwards

Perfect, tender, flavorful and good sauce.

I need to figure out how to strain out the little protein clumps from the bag sauce

I will probably do a few bags next time and then quick cool and freeze

so I can just put them in the wok next time.

[NY_Amateur]

I have read this entire thread at least twice now as well as learned about as much as I can about sous vide on the internet and I still have quite a few questions that I would like to pose to the community. Any help would be appreciated.

It's interesting what you think you know versus what you actually know when you start cooking this stuff, I had the chance to try compressed watermelon and I asked the chef how inches of mercury his machine pulled when he compressed it and then I found out that modern machines are measured in millibars (close to a full vacuum, 20 millibars, about 29.33" of Mercury or .59" depending on you count), so needless to say I have a lot to learn and look forward to doing so.

Once I tried the compressed watermelon I noticed that it tasted about the same as the watermelon I compressed at home and so I am curious as to whether or not the extra vacuum is worth it.

Once I figure out how to post images on here I will upload the photos I took of the watermelon I compressed if anyone is interested. It was interesting that the physical size did not shrink at all but I emailed Ideas In Food about that and Alexander replied that the compression is at the cellular level, I assumed this would lead to macro scale compression but apparently not. That may be helpful for someone trying to replicate this in an edge sealer like mine.

Can anyone confirm for me the difference in compressed watermelon (or other soft fruits) at varying levels of vacuum? Is the difference noticeable between say 300 millibars, 200 millibars, 150millibars, 100, ~0?

FYI I got a vacuum guage and measured the aux port on my foodsaver v2840 to be pulling approximately 200 millibars or 23" of Hg. I had read that someone said theirs could pull 65mb (is that the right way to abbreviate that?) which is ~28".

Secondly, I just got an old but working Lauda B and will be cleaning that tonight/tomorrow so I am excited to try some of the longer cooking recipes as well as those requiring more precise temp control than what I can realistically achieve with a pot on the stove.

But for the cleaning, is it safe to circulate 80% isopropyl /citranox/bleach? or should i just soak it in these wonder substances for a while? I plan on doing at least the bleach and the citranox, can anyone else recommend things to use?

Third, I have designs to build an at home vacuum chamber for significantly less then a professional one, this will probably end up terrible and I will have to make do without it but my main question is, is a bag in a closed impulse sealer able to be vacuumed in a chamber or is the seal tight enough (on the impulse sealer when closed but not sealing) to make this unfeasible?

Again thanks to everyone who has posted in this thread as you have been immeasurably helpful especially DouglasBaldwin, NathanM and Pounce!

[sasquatch]

I am building a stainless steel tank to hold 12 racks of pork spareribs. I will position the ribs standing up vertically in 2 rows of 6 ribs each. Do you guys think I should position my immersion circulator in the center? Or near the corner walls of the tank (like the tank that Polyscience has)? And why? Thank you.

[DouglasBaldwin]

So long as the ribs are completely submerged and there is a reasonable amount of space between them, it doesn't matter where the immersion circulator (IC) is located. Since you are concerned, then connect a tube to the outtake of the pump so that the intake is on one side of the tank and the outtake is on the other side of the tank. (This of course assumes that your IC is fairly new, since the pumps on old ICs can be rather anemic.)

Since that is a lot of meat, you may need to incorporate additional heating elements into your tank design (controlled with a bang-bang temperature controller set just below your desired water bath temperature). It is also very important that you use a lid (say Lexan or metal) to reduce the workload of the IC (since evaporation uses a lot of energy).

[nathanm]

---

Once I tried the compressed watermelon I noticed that it tasted about the same as the watermelon I compressed at home and so I am curious as to whether or not the extra vacuum is worth it.

....

Can anyone confirm for me the difference in compressed watermelon (or other soft fruits) at varying levels of vacuum? Is the difference noticeable between say 300 millibars, 200 millibars, 150millibars, 100,  ~0?

FYI I got a vacuum guage and measured the aux port on my foodsaver v2840 to be pulling approximately 200 millibars or 23" of Hg. I had read that someone said theirs could pull 65mb (is that the right way to abbreviate that?) which is ~28".

So here is info on pressure and vacuum.

Pressure is measured in many units. Imperial units are psi - pound per square inch.

The metric unit is Pascal (Pa) which is 1 Newton per square meter.

1 Newton is the force equivalent of 102.041 grams.

Bar is another pressure unit, which is designed so that 1 Bar is approximately equal to atmospheric pressure.

1 Millibar = 1/1000 bar - abbreviated mbar

Torr is another vacuum pressure unit. 1 Torr = 51.715 psi = 133.322 Pa

The point of a Torr is that 1 Torr is approximately = 1 mm of Mercury, written mmHg

The reason for this is that barometers, and many other old fashioned pressure gages would use mercury in a tube to measure pressure. 1 mm height difference corresponds to a certain pressure.

In Imperial units, you have inches of Mercury, written inHg

Ok that is units. The pressure due to the atmosphere depends on height above sealevel and the weather. The standardized value is

Atmospheric pressure (atm) = 14.7 lbs / square inch (psi) = 101325 Pascal (Pa) = 760 Torr = 760 mmHg = 29.92 inHg

Technically a 1 Bar = 100,000 Pa, so 1 Bar is slightly different than actual atmospheric pressure.

----------------------

OK, so now on to your watermelon question.

200 mbar = 20% of atmospheric pressure. So the net pressure on the outside of your bag during compression is about 12 lbs per square inch (80% of 15).

Of course the bag comes into equilibrium quickly, so when you put a bag with interior vacuum of 200 mbar into the air at 1000 mbar, it crushes down until the force is equalized at atmospheric pressure. But during the compression/suction cycle there is 12 psi net force on the outside of the bag.

A perfect vacuum would get you an additional 3 lbs/square inch.

So, the question of whether the extra vacuum is worth it depends on whether you need the extra 3 lbs/square inch of pressure.

-----------------------

The compression is not really at at a cellular level. The cells do not get smaller. It is actually about compressing space between cells - watermelon is a foam-like structure .

-----------------------

When you seal food in a vacuum bag for storage the difference between 200 mbar and 20 mbar is that you are removing more oxygen from the bag. At 20 mbar there is a factor of 10 less oxygen then at 200 mbar.

So if you buy supermarket cheese, it comes vacuum sealed to the much lower vacuum, because oxygen makes the cheese rancid and every factor of 10 counts.

This difference is not important for most sous vide cooking however.

[NY_Amateur]

Ok now it all makes sense when its laid out like that, thank you very much for that. Now the question is to figure out how much difference that 3psi makes.

On a somewhat related note the NYT article on Thomas Keller / Sous Vide (http://www.nytimes.com/2005/08/14/magazine/14CRYOVAC.html) mentions that the watermelon is "cryovacked" at 20 pounds per square centimeter.

Besides the odd mix of imperial and metric this works out to be something like 129 PSI which is a little over 9 atmospheres. 14.7 PSI however works out to be 2.27 pounds per square centimeter which makes some sense, misplaced decimal becomes 22.7 rounded down to about 20 for the average reader.

I am not aware however of a vacuum chamber sealer that can also pressurize the chamber, do such things exist and are they ever used? Or is this just a case of something being lost from spoken to written.

EDIT: One more question, hopefully I will be contributing soon instead of just asking. I made striped bass the other day and it was well cooked after 25 minutes at ~47 C (using a pot on the stove for this so there was significant temperature fluctuations) but not at all flaky, instead it was much more meaty. Was this a function of the fish or cooking method?

[slkinsey]

Ths short answer is that either Keller doesn't know what he is talking about, or he was misquoted. The most pressure you can get on the watermelon is atmospheric pressure (14.7 PSI) unless you do something to increase the pressure.