Sous Vide: Recipes, Techniques & Equipment (Part 2)

[nathanm]

MichaelB, I've searched for the shrink bags before and could only find them in huge quanities. Suitable for commercial operations but way more than I need. I specifically asked Nathan and he didn't know of any.

It's true - I don't know of a good source of shrink bags at retail. Cryovac makes them for industrial food packaging, and I got some samples from them. It is a bit bizarre actually that nobody seems to resell them, even in butcher supply catalogs.

They are useful for cases where you want to mold something or hold it together.

[nathanm]

I figured that to be safe, that was what I was going to have to do.

I think you have to toss the short ribs...Clostridium botulinum...it's a risk you can't take.

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When in doubt, throw it out!

Botulism is possible but unlikely in that circumstance. Clostridium perfringens is a possibility that is more likely - it takes heat better, and is more acid tolerant. It has been implicated in cases where a large piece of meat (ham or turkey) is allowed to cool too slowly.

To reply to a comment about toxins in the thread

It sounds like the short ribs were at reasonable temperature for a while, then 4 hours at a dangerous temperature. The first period of time would kill all of the bacteria - that isn't an issue.

The problem are spores - which are formed by many bacteria, including Clostridium botulinum (botulism) and Clostridium perfringens. The spores are really hard to kill - you need very high temp for a long time. That's why you typically use a pressure cooker when doing canning.

The danger here is that spores germinated and then grew in the 4 hours that the ribs were at dangerously low temperatures. Toxins are then formed by the bacteria. The toxins are the thing that you watch out for in the case of anaerobic spore forming bacteria like either of the Clostridium.

However, unlike a comment in the thread, the toxins ARE destroyed by heat. Botulism toxin (by the way, it is the same stuff in Botox injections for cosmetic purposes) is destroyed by about 10 minutes at 80C.

Finally, remember that human body temperature is 37C, and lots of bugs that makes us sick grow best around that temperature. So you do not want to leave things at that temperature or below for very long.

[ChefJohnny]

Fortunately Clostridium botulinum  is killed by an acid environment, so if your recipe contains vinegar or lemon juice or wine its probably (but not definitely OK). Its why many old recipes and pickles are acidic.  Even so I would not feed them to the very old or young or the immune challenged. Might eat them myself tho.

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True, but the botulin toxin is not killed by heat or acidic or anaerobic environments. Its not the "bug" that you really need to worry about, its the toxin.

- Chef Johnny

[nathanm]

True, but the botulin toxin is not killed by heat or acidic or anaerobic environments. Its not the "bug" that you really need to worry about, its the toxin.

- Chef Johnny

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The toxin is not alive, but it is destroyed by heat. A lot less heat than it takes to kill the spores, but still a substantial amount. 80C for 10 minutes is the usual recommendation, although like all such reactions one can go for a longer amount of time at lower temp (to a point), or a shorter time at higher temp.

[masters888]

Hi guys,

I'm new to this site and want to thank you all for the great reading over the last few weeks.

We have an Indian restaurant in Australia and have had a chamber vacuum machine for a few years for use in marinating and food storage to retain moisture etc.

Recently we've discovered SV and have bought our first 20 litre circulating water bath a few days ago. We did our first experiment today with lamb chops and we're delighted with the result. (58°c or 136°f for 6 hours with garlic, rosemary and EVOO) Hardly Indian I know, but this is just the start. Meat was very tasty, however a bit firmer than we would usually like, though not tough at all.

One of our chefs wants to do a (boneless) roast leg of lamb for a family special occasion in 2 days. He has asked if we can do a "Raan". This is usually done by boiling the lamb until tender then roasting in a tandoori oven with the spices basted over the meat while roasting. He wants us to do it SV.

We yesterday we placed the leg of lamb (it weighs about 2 kg / 4.4lb) with the usual spice marinade into a cryovac bag to marinate under vacuum in refrigerator. Today we are ready to SV and we're not sure at what temp or for how long we should leave in the bath.

We want to SV in the marinade. Usually the marinade has rum as part of the recipe. We left the rum out because I recall someone on this site mentioning that alcohol affects the texture of the meat during SV process

Then we want to follow up after the SV with finishing off the outside roast in our combi oven at say 220°C, and again basting with the marinade while roasting the outside.

Does anyone have any experience with what we about to try and have any hints that may help?

[nathanm]

Time and temperature depend on what effect you want.

If the meat is tender to begin with, and you want it medium rare, then 131F/55C. Time by the tables elswhere in the thread - probably a couple hours.

If the meat needs to be tenderized a bit, then 24 - 48 hours at 131F/55C.

Your lamb chop experiment was at 136F/58C. If you like that result, but it was not tender enough then try for 12 to 24 hours at that temp. I prefer to have the temp lower but that is just personal preference. The lamb I get in the US (including some from Australia or NZ) is pretty tender, but perhaps that is just the export meat.

However if your chef normally boils the lamb, then he is expecting gray meat, and will be surprised by the pink medium rare look you get at that temp.

In that case I would try 158F/70C for 8 hours. You could also try 176F/80C for 6-8 hours.

I generally do lamb shanks and 70C for 12 hours. Shanks are tougher than leg meat.

The higher the temperature, the more the meat will be tenderized and have a "stewed meat" texture. If you go for too long, then it will fall off the bone and be too tender to the point that it is falling apart. Unfortunately there isn't any single recommendation because it depends on two variables that I don't know:

- How tough is your lamb to begin with?

- What sort of texture effect do you want?

Searing the outside in a very hot oven afterward should work very well.

[masters888]

The lamb leg is tender to begin with and has had the bone removed.

The expected result would normally be well done gray meat and very (falling apart) tender, though I've warned them to expect a pink result with more taste than they normally get. The lamb chops colour started to show them the way.

Part of the marinade recipe is pineapple, I suspect because it aids in tenderising. Along with yoghurt, a little oil, garam masala and other spices. Not exactly sure which others they used at the moment.

You're right about the chef expecting gray meat, though I don't think he would object to the meat being pinkish as long as it's tender and tasty. I guess he would prefer the meat to be more medium than too rare. ( the bloody look scares them a little)

BTW shanks are marinating right now ready for the next experiment, followed by a Beef Madras and Rogan Josh curries.

[AlexP]

Does anyone have some time/temperatures for squid?

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I would love to know if somebody has cooked squid Sous Vide. Anybody can give us some temperatures / times?

Thanks in advance

[cricklewood]

AlexP, at work we cook baby squid sous-vide, after they are cleaned bodies are drained to remove excess moisture and then bagged with a little olive oil and some aromatics (bay and some herbs) we don't use a circulator for this so I can't give you a precise temp. I get the water to a good simmer and then put the pot on the plancha which keeps the temp steady, they usually cook for about 2 hours since it's baby squid we don't usually go much longer than this but the result is worth it, tender and not as chewy as if they we're cooked a la minute. I imagine if you used larger squid or octopus that a longer time would be needed but would work well, try between 65-70 C and see.

Edited August 18, 2007 by cricklewood (log)

[AlexP]

Thanks for the suggestions. I have tried in the past at 40 C for 30 minutes, but that was no enough. After the bath, I stuffed them with some squid ink rice and sauted them.... As you said, I need to increase temperature and time.

[MichaelB]

It's true - I don't know of a good source of shrink bags at retail.  Cryovac makes them for industrial food packaging, and I got some samples from them.  It is a bit bizarre actually that nobody seems to resell them, even in butcher supply catalogs.

They are useful for cases where you want to mold something or hold it together.

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OK, I managed to purchase a case (1,000 count) of 9 inch by 12 inch shrink bags. I am not quite sure yet what they cost me, but they were not that much more expensive than regular vacuum pouches.

It seems there are perhaps only two domestic manufacturers of these things. And a friend buys his regular bags direct from this manufacturer. All the shrink bags are manufactured to order and the minimums are quite high. I was able to tack a case onto an already scheduled order.

The quantity is more than I may ever use. But at least I have plenty to play around with.

[nathanm]

...

You're right about the chef expecting gray meat, though I don't think he would object to the meat being pinkish as long as it's tender and tasty.  I guess he would prefer the meat to be more medium than too rare. ( the bloody look scares them a little)

...

BTW shanks are marinating right now ready for the next experiment, followed by a Beef Madras and  Rogan Josh curries.

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Well, how did it all turn out??

[alwang]

I did some short ribs over the weekend at 55C for 48 hours, followed by a quick pan seat. While the meat was a nice pink, I felt that there was a lot of liquid left in the bag, and the meat was drier than I would have liked. I find this only happens for certain cuts at extended cooking times: I did some lamb neck at the same time and temperature, and that came out tender and juicy.

Would it have helped to rest the meat in the bag for a few minutes before the sear, or is there some other way to allow some of the juices to be reabsorbed by the meat?

[nathanm]

Would it have helped to rest the meat in the bag for a few minutes before the sear, or is there some other way to allow some of the juices to be reabsorbed by the meat?

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No, after cooking for 48 hours there is not much point in further "resting".

Usually what "resting" when you roast or grill is time for the temperature to equibrate and even out. The very hot surface temperature needs to cool down, and as that happens some juice will be sucked back in.

However, that only occurs when the suface is above boiling point (i.e. grill, plancha, broiler, hot oven).

[slkinsey]

Al, did you sear the short ribs right out of the bag? If I'm going to be pan-searing (as opposed to using a blowtorch) I usually wait for the meat to cool down a while. Otherwise, the pan searing will probably take the temperature of the meat too high. You'll still have the pink interior because the LT/LT cooking "fixed" the color, but you might end up with a dryer texture that you don't want.

[alwang]

Yeah, I pretty much just seared it right out of the bag. That's an interesting explanation: I'll try letting cool down next time. I will say though, I don't really have this problem when I do short-time sous vide, like fish or steaks, and I also sear straight out of the bag.

[MaxH]

An equipment tip, and a caution. This thread is so vast, I haven't been able to read it all. But here are two pieces of information that have circulated elsewhere. I'd guess the "caution" part is already familiar here, so I'll mention it first and briefly.

Caution: In discussing the situation below, a friend, (high-profile) academic biologist who is familiar with sous-vide in practice, reminded us that sous-vide inherently cooks foods slightly above the temperature where anaerobic pathogens multiply, and that these are among the very worst food health hazards. They include the infamous C. botulinum (mentioned here) but others too. Therefore, keeping correct uniform temperature regulation can be a matter of life and death.

The tip:

Professionals that I know use laboratory water baths for temperature regulation in sous-vide in their restaurants. A much cheaper route to the same kind of regulation was suggested by Robert Wright of a reputable and eclectic silicon-valley laboratory-equipment dealer I deal with Lab-Pro Inc. (Reliable source of many temperature instruments including longterm min-max monitors, compact temperature data loggers -- both good for wine storage and transport -- and infrared non-contact temperature meters.)

I told Robert he might get inquiries about water baths for sous-vide. Sure, he said, I can sell them a lab water bath if they want one, with lots of features not used in sous-vide. But for this temperature range, he said, you can assemble a well-regulated water bath far more cheaply. He then showed me a modern electronic temperature-control module, hand-held. It has a power cord on one end, and a sensor at the end of a wire. You plug the controller into the wall, plug a heater of your choice into the module (up to its rated power limit), program the module, and put the temperature probe at the point whose temperature you want to regulate. Price something like $90. "A crock pot would be ideal, to build a water bath for this temperature range." They're cheap, too. This compares to a new laboratory water bath starting around $1000.

I haven't tried this, but it makes sense, especially if a lab water bath uses a similar temperature sensor. Any temperature regulation system has three basic elements. A powered heater or cooler, a temperature sensor and controller that cycles the power on and off, and a thermal mass that's heated or cooled. If the thermal mass is large and thermally conductive (like a pot of water), and you keep it covered and relatively insulated from outside temperatures, its own thermal inertia aids in keeping temperature steady, and its conductivity aids in keeping the temperature spatially uniform.

Again the suggestion was from Robert Wright, President, Lab-Pro Inc., Sunnyvale, California. www.labproinc.com

[slkinsey]

I'm not sure that I buy the "spatially uniform" bit. The reason lab heaters circulate the water is to maintain all the water at the same temperature. For something like a crock pot, I have my doubts as to whether it could maintain the temperature with any precision and uniformity. For one, I think the very nature of the way the heating element works would likely cause the temperature to overshoot with some frequency, and the temperature would likely swing with a range of several degrees. Now, your friend may not think that temperature accuracy of +/- 5C is a big deal, but it can make a really big deal on what you're cooking when you're trying to take advantage of the technology's full power.

I'd also be curious if you could ask your friend what features, exactly, a recirculating water bath heater would have that would not be used in sous-vide cooking. My Lauda has settings for temperature and fail-safe cutoff temperature, and it recirculates the water (mine is a stand-alone heater that I can clip on to any water vessel, rather than an all-in-one water bath). That's pretty much all it does, and it's accurate to 0.1 degrees C. All of these features I'd say are used in sous-vide cooking.

[jackal10]

Sam

I agress that +/- 5C is a big deal, and the difference between raw and cooked or rare and overcooked.

A crock pot might work if the controller was a PID (http://en.wikipedia.org/wiki/PID_controller ) with analog output and the food was on a rack with sufficient circulation space under it.

Unfortunately most cheap remperature controllers are bang-bang on/off and that will cause large local temperature variations.

For restaurant use the thing has to be chef proof, and that means things like splash proof, easy clean and with controls that lock. Fortunately many lab suppliers are now making food versions. I have one from Grant Instruments

[slkinsey]

The question is whether a PID controller/crock pot is sufficently low priced to make it worth choosing over just picking up a recirculating water bath heater on eBay. And, needless to say, whether you can use the crock pot setup without having to know electronics (a recirculating water bath heater is more or less "plug and play").

[jmolinari]

slkinsey, you cna pick up a PID on ebay for $50, a crock pot for $20, thermocouple, and wires and random parts, MAYBE $50.

It will take a little knowledge, but def. cheaper than a water bath on ebay...isn't it?

But it doesn't circulate.

[MaxH]

The reason lab heaters circulate the water is to maintain all the water at the same temperature.

Do sous-vide cooks (I'm not one) routinely use the circulating type? Bob Wright at Lab-Pro remarked (just now when I phoned him) that he sells two types of complete temperature regulating equipment suitable for water. The thermal circulating units (maybe including that Lauda?) are very precise, but more expensive, starting around $700-800 depending on size. The other type is a regulated water reservoir without circulation, starting around $350.

I think the very nature of the way [a crock-pot] heating element works would likely cause the temperature to overshoot with some frequency, and the temperature would likely swing with a range of several degrees.

Sam and also jackal10, that may or may not be relevant (do you have data?)

Everyone please keep in mind that almost every feedback-regulated temperature controller in daily life employs an on-off ("bang-bang") heating or cooling element. I know a little about these things. The magnitude of residual temperature ripple reflects several factors including dynamics (time-lag effects etc.) that are outside the controller module, and how cleverly the controller compensates for them. Comments earlier proceeded from assumption of +/- 5 deg C (+/- 9 deg F) fluctuation -- bad for cooking, I'd guess too. But I've no idea if that's typical of the practical system I described, whose controller module could, nowadays, be sophisticated (even adaptive or nonlinear optimal control). I'm not even sure the module is a bang-bang controller, but I assumed as much for the usual reasons (economy, efficiency). It would be worthwhile for someone who wants actually to test the idea to try it or at least research it further.

The question is whether a ... controller/crock pot is sufficently low priced to make it worth choosing over just picking up a recirculating water bath heater on eBay. [see caution below -- MH] ... a recirculating water bath heater is more or less "plug and play".

Yes, the module that I saw briefly is similarly "plug and play," meant for the same people who use lab water baths. The difference would be that you must place, or install, the probe inside the crock-pot.

Some context and another caution: This idea arose after I showed the lab supply dealer (who gladly sells lab water baths too, I hope that was clear) -- Tara Duggan's SF Chronicle article cited upthread. The dealer's response was that he thought you might get similar regulation for much less money than a new water bath. The caution that appeared in a subsequent Chronicle food section, which I hope was cited here too, came from a working scientist (and amateur cook). She strongly advised prospective sous-vide cooks never to employ a used laboratory water bath for cooking, since it may have carried unknown and (she said) dangerous contents in laboratory service, with no allowance for later use for food.

I'd also be curious if you could ask your friend what features ...

To clarify, it's not a friend but the head of a well-known silicon-valley laboratory equipment dealer, Lab-Pro Incorporated. I'm just a customer. You can as easily ask Robert Wright that question as I can. (I don't remember the extra features, he did mention some at the time, back in May). I did phone him and speak briefly today, as summarized in first pph. Remember, this gentleman is in the business of selling lab water baths too, it was just his suggestion to save customers money if it still gave adequate regulation. (The firm is like that, by the way). Summary: Take an existing, inexpensive heater unit with the right range and a different original purpose, and instead of relying on its own cheap thermostatic control, supplement it with an outboard, accurate high-tech one -- the combination potentially being far cheaper than any kind of lab water bath, all things being equal.

[DocDougherty]

I agress that +/- 5C is a big deal, and the difference between raw and cooked or rare and overcooked.

A crock pot might work if the controller was a PID (http://en.wikipedia.org/wiki/PID_controller ) with analog output and the food was on a rack with sufficient circulation space under it.

Unfortunately most cheap remperature controllers are bang-bang on/off and that will cause large local temperature variations.

For restaurant use the thing has to be chef proof, and that means things like splash proof, easy clean and with controls that lock. Fortunately many lab suppliers are now making food versions. I have one from Grant Instruments

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Thanks for the pointer to the Grant Instruments sous vide tanks. This is the first time I have looked at them. It appears that they have done the engineering quite well, what with a 1 deg control band, thermal convection instead of a circulation pump, heater on the bottom to drive the convection (vs on the side as with a crock pot), stainless all around and a relatively tight lid with no cutouts for stuff to pass through. Somebody else will copy this with an integrated plastic or powder coated steel shell and cut the price, but at $900 for a 3 gal tank it is not much less expensive than a new Lauda circulator. You certainly don't need 0.1C of accuracy for sous vide (the Lauda controls to much better than 0.1C after it gets up to temperature), but the flexibility of being able to use it in a big tank or a small pot, easy storage, etc. would make it my preference even if I was buying it new today. Luckily I don't have to worry about chef-proofing, but I understand the concept. The price point for a mass market sous vide system is probably around $300, which means that it needs to cost less than $60 to make which is quite a challenge if you have any custom parts. I think that is about where the Grant Instruments unit is (maybe less), but they are not attempting to sell it at Target or Walmart.

Doc

[Kouign Aman]

The caution  that appeared in a subsequent Chronicle food section, which I hope was cited here too, came from a working scientist (and amateur cook). She strongly advised prospective sous-vide cooks never to employ a used laboratory water bath for cooking, since it may have carried unknown and (she said) dangerous contents in laboratory service, with no allowance for later use for food.

I dont cook with this method, and I'm not advocating anyone ignore this advice. I personally don't understand the risk however. Waterbaths and circulators are tricky but not impossible to clean, and the food is cooked completed sealed into a leak-proof bag. Worst case, it seems to me, would mean being carefully to fully rinse or dry the bag prior to opening. That said, I'd still probably want to know what the lab was using the waterbath for, before I bought it. I know from nothing about organic/inorganic laboratory chemistry, and wouldn't want to risk nasties that bind themselves into the bag.

It seems to me a bigger risk is from leaving the waterbath full of water day in and out, and watching it grow a biofilm aka pond scum. Some of the lab models hold a lot of water and I can see someone being reluctant to change it out. Smaller modules more suitable for personal use probably wouldnt be in that situation.

My practical experience with heated circulating waterbaths is +/- 0.5C regardless of stated performance. These are large models, with large volumes of room temp stuff being added and warm stuff being removed fairly often. Its pretty amazing how well they work. Being left alone and covered, I expect there is much greater accuracy, such as other posters are describing.

[project]

'Optimal control' and bang-bang controllers?

Good, grief, my Ph.D. dissertation was on stochastic optimal control, but I never thought it would be used in cooking!

For a controller to be 'optimal', need to specify essentially the context, assumptions, etc. That is, in control theory, 'optimality' is a mathematical property, and, to get any such conclusions, mathematics needs some assumptions.

Yes, in principle, keeping something 'constant' in, say, temperature, voltage, position, speed, is a problem in control theory.

When I was discussing optimal control with some experts -- MIT, Cornell, Brown -- the 'practical engineering' view was that optimal controllers are often bang-bang controllers. This fact can play havoc with the results in the elementary theory of differential equations!

As a practical matter, if I were making a constant temperature water bath and was getting too much 'overshoot', then I would reduce the power level of my heat source so that the source was on, say, about 50% of the time, in the context.

To adjust the power, might use a variable transformer, a common piece of electrical laboratory equipment.

Of course, another way to 'adjust' the power is just to use a bang-bang controller that turns on and off at relatively high frequency. One way to do this is to take the approach of a 'switching power supply'.

For a practical design point, might mount the heating element at the 'intake' of the water circulator and mount the temperature sensor a the 'output' of the water circulator. Generally want relatively rapid water circulation and a relatively small distance between the heating element and the temperature sensor.

When I was at the US National Institute of Standards and Technology, our group had a spectrograph we wanted to keep at a constant temperature within 0.01 C. For this, we used a bang-bang controller and a room deep in the basement and kept the door closed.

When I was in a biophysics laboratory, we had a lot of constant temperature water baths. These were all just 'home-brew'. Each bath was in a big, heavy glass jar. We used bang-bang controllers. The heating element was an incandescent light bulb with the glass end in the water and the electrical connections out of the water. For water circulation, there was a little electric motor with a shaft with a propeller on the end. Can get similar shafts intended for mixing paint.

Gee, you guys are considering MEASURING things, and even getting NUMERICAL answers! WOW! I was concluding that any mention of measurements or numbers was strongly against the norms of the 'foodie' community! Guys, be careful or might be criticized, chastised, and ostracized!