1176 replies to this topic

[PedroG]

Sous vide in original plastic packaging?
I have had great success with SV prep of steak, salmon, chicken etc . . . as well as pork tenderloin. In all cases I have used the Ziploc vacuum bags with the manual air extractor. I am holding a Hormel pork tenderloin, packaged in heavy vacuum sealed plastic. Is there a reason NOT to just drop this into my SousVideMagic-controlled slow cooker? Is there something about either the composition of the plastic or its thickness that would make it inappropriate?

I did this several times, e.g. bacon in the original plastic bag for 3-4h at 78°C, ditto with sausages. No problem so far. With pork tenderloin you may not want to exceed 52°C, should not make a problem in the original bag. Food is usually packed in PA/PE or PE which have no additives, and no longer in PVC (with phthalates as plasticizers which give the typical "plastic odor").

[PedroG]

HI all
I don't have a water bath or anything that's accurate.

has anyone had success with braises that don't require such accurate control of temperatures?

I'm thinking of sticking my bags submerged in water and then into my oven at 70c or so.

Exactly!
See http://sousvide.wiki...nsive_equipment
For water temp. 55°C I had to set the oven temp. to about 70°C, for water temp. 77°C you need oven temp. above 100°C; as in traditional braises, water evaporation will prevent the water bath to go significantly above 80°C even with higher oven temperatures.

My suspicion is that these numbers might vary somewhat, depending on your oven and pan.
A fan oven is going to give more evaporation, but also greater heat transfer.
Then there's the whole black versus white/shiny pan thing, which will depend on the amount of radiant heating, particularly from exposed electric elements or gas flames ...


Anyway, any sort of thermometer (meat roasting or jam-making for example) that is not going to be damaged by being in a low-set oven, is going to give you a pretty fair idea of what temperature your water bath is actually achieving.
Just don't rely on its accuracy for food safety - keep away from the edge ...

I used a dual-sensor-thermometer "http://www.outdoorch...3,67&prod_id=1" (sorry, you have to copy-paste the link, as the editor would break it at the comma) for the oven - waterpot - method; knowing that it was wrong by 1°C. This showed me the oven temperature and the water temperature. http://www.mastrad.fr/art.php?id=441 worked as well.
However, avoid bimetallic coil thermometers, they are not a satisfactory device for measuring food temperatures, see http://www.hi-tm.com.../Bimet-pic.html .

[mark28209]

Terrific! Although I usually want to add my aromatic bits and pieces to the bag, an occasional simplification is welcomed.

On a related topic, I have done my previous pork tenderloins to a somewhat higher temp, closer to 60/140. I've been collecting various temp charts, Keller, Baldwin, etc., etc. Do you know of a compendium that you rely on? I find Baldwin's concerns re safety lead to higher recommendations than others, have found some salmon reco's (e.g. 46/115) far too rare for my preferences (I'm now at 51.5/125). How are you approaching this?

Again thanks for your response re the packaging!

Cheers,

Mark

[PedroG]

...have found some salmon reco's (e.g. 46/115) far too rare for my preferences (I'm now at 51.5/125). How are you approaching this?

One thing about cooking at the lower temperatures as well is that the salmon tastes lukewarm, which can be unappealing for many people.

For this reason salmon is the one item that I cook at a higher temperature than the end temperature and carefully time the cooking.

Try 68C for seven minutes. This will give a reasonable core temperature while leaving the fish itself at a serving temperature people are more comfortable with.

One thing more, if you are vacuum packing salmon, make sure that you treat the fish lightly. If it compresses, it will not give as pleasing a texture.

I bag salmon with minimal vacuum or just with a Ziploc bag, cook to 45-48°C, lay the bag on a cutting board and cut it open with a sharp knife on all 4 sides, remove the upper plastic layer and slide the salmon directly from the plastic into a skillet with almost smoking hot grape seed oil or rice bran oil and sear on both sides, this will automatically give a more comfortable serving temperature.

[PedroG]

Terrific! Although I usually want to add my aromatic bits and pieces to the bag, an occasional simplification is welcomed.

On a related topic, I have done my previous pork tenderloins to a somewhat higher temp, closer to 60/140. I've been collecting various temp charts, Keller, Baldwin, etc., etc. Do you know of a compendium that you rely on? I find Baldwin's concerns re safety lead to higher recommendations than others, have found some salmon reco's (e.g. 46/115) far too rare for my preferences (I'm now at 51.5/125). How are you approaching this?

Again thanks for your response re the packaging!

Cheers,

Mark

Most temperature recommendations are too high, maybe for liability reasons.
My preferences are 45-48°C for fish, 52°C for tender pork, 55°C for beef and lamb, 60.5°C for chicken, 78°C for bacon and sausages, and that's it. Of course always with post-searing. Cooking times according to thickness (Douglas Baldwin's tables).
Pedro

P.S. As I have an ISO-calibrated high-precision thermometer accurate to 0.03°C, my SousVideMagics are calibrated to 0.1°C. Without a calibrated thermometer, using 56°C instead of 55°C for long-time-cooking (48h-brisket etc.) might be a safety option.

Edited by PedroG, 15 April 2010 - 06:43 PM.

[Merridith]

OK, now I am really confused. 52C for tender pork sounds very, very rare if not raw to me. So apropos of our recent discussion, may I assume you are not cooking it for more than 4 hours? I'm not sure I understand what "tender pork" is other than a tenderloin. Most pork chops seem pretty tough to me even when brined in a 7% brine for 3 hours before bagging (how I handle my pork chops). Also, at 52C, how long are you cooking say a 15 cm thick slab? I cooked a boneless pork shoulder for 48 hours at 60C it was still plenty pink, juicy and tender. I have done 10cm chops for one hour at 58C, I would like to do it a little less (say 57C)because the loin chops I use are so lean. What would you recommend. Thanks.

[Merridith]

Another question: Would the Thermapen or other thermocouple type digital IR thermometer be acceptable for calibration? I have, by the way, tested my SVS with about 4 different thermometers (including two digital IR thermometers, an old analogue IR type and a basic candy thermometer) just to see if the thermometers agree with the read-out on the SVS and the digital IR thermometers always agreed within .1C.

[JNS-Eats]

New to the forum, but have read most of the sous vide topic. Question about cooking eggs. I have a SVS and have done eggs a few times at 65c. Love how they come out. My question is that I've read that once an egg is pasteurized it can be stored in the refrigerator just like raw eggs. I'm a bit confused on this. If you do this, when it's time to eat them, do you re-heat them in the SVS back to the same temp (i.e. 65c)? How long can you actually keep them in the refrigerator? The only negative about cooking the eggs is how long they take (i.e. 1 hour), but would love to have many already cooked that I could just "re-heat" and eat in the morning on some toast.

Thanks!

[jk1002]

I did different types of salmon as well as chilian sea bass at 60.5c timed to hit pasteurization.

The wild coho tonight came out horrible dry. The seas bass was ok, other types of salmonnas well.

I googled sushi grade and it seems that the term is not really defined by the fda. It also seems that if the fish was previously frozen that this wouod kill off possible parasites.

So what is the actual risk if i lets say do a salmon at 50c? I know pasteurization is not really an option at these low temps since i would be in the danger zone too long.

From a safety prospective, assuming i dont want to go aove 55 and pasteurize are there different levels of time and temperature that lead to higher safety? Or can i do whatever I like if i stray from pasteurization.

I noted that Keller is all over the place in his recipes but he is staying far away from pasteurization.

[jackal10]

This might help: http://www.cookingis...ow-temp-primer/ with pictures.

"Salmon cooked at various temperatures. Interesting: fish often go through two zones of goodness: a low temp zone usually described as having a fudge-y texture, and a higher temp zone that makes a more classical texture. Fish cooked between these zones squeaks when you chew it. The exact temperature of the two zones depends on the fish itself, the season in which it was caught, the fat content, etc."

[BadRabbit]

I can find beef back ribs all the time but seldom see short ribs. Can they be cooked sous vide using the same recipe or do I need to make adjustments?

[jk1002]

I saw the cookingissue post. That doesn't go into the safety concerns though and I know for sure they have better fish then what I pick up at my local wholefoods.

Question is, what risk remains assuming they had it frozen properly before selling it and they stored it like they should.

The Keller book doesn't comfort me much since as the FCI he has access to excellent fish.

Cheers
JK

[e_monster]

I did different types of salmon as well as chilian sea bass at 60.5c timed to hit pasteurization.

The wild coho tonight came out horrible dry. The seas bass was ok, other types of salmonnas well.

I googled sushi grade and it seems that the term is not really defined by the fda. It also seems that if the fish was previously frozen that this wouod kill off possible parasites.

So what is the actual risk if i lets say do a salmon at 50c? I know pasteurization is not really an option at these low temps since i would be in the danger zone too long.

From a safety prospective, assuming i dont want to go aove 55 and pasteurize are there different levels of time and temperature that lead to higher safety? Or can i do whatever I like if i stray from pasteurization.

I noted that Keller is all over the place in his recipes but he is staying far away from pasteurization.

In my opinion, if you use good quality salmon and freeze it for 24 hours to kill the parasites, you are much better off not pasteurizing it. I find that for salmon 116F for about 20 minutes is extraordinary and I have served it many times and people always wish that I had prepared more. Brine it for 10 to 20 minutes as Doug Baldwin indicates it in his sous-vide guide.

I put a little liquid smoke in the bag and sprinkle the salmon with a small amount of garlic powder and put some strips of lemon zest in the bag or a few thin slices of lemon.

[PedroG]

Most temperature recommendations are too high, maybe for liability reasons.
My preferences are 45-48°C for fish, 52°C for tender pork, 55°C for beef and lamb, 60.5°C for chicken, 78°C for bacon and sausages, and that's it. Of course always with post-searing. Cooking times according to thickness (Douglas Baldwin's tables).
Pedro
P.S. As I have an ISO-calibrated high-precision thermometer accurate to 0.03°C, my SousVideMagics are calibrated to 0.1°C. Without a calibrated thermometer, using 56°C instead of 55°C for long-time-cooking (48h-brisket etc.) might be a safety option.

OK, now I am really confused. 52C for tender pork sounds very, very rare if not raw to me. So apropos of our recent discussion, may I assume you are not cooking it for more than 4 hours? I'm not sure I understand what "tender pork" is other than a tenderloin. Most pork chops seem pretty tough to me even when brined in a 7% brine for 3 hours before bagging (how I handle my pork chops). Also, at 52C, how long are you cooking say a 15 cm thick slab? I cooked a boneless pork shoulder for 48 hours at 60C it was still plenty pink, juicy and tender. I have done 10cm chops for one hour at 58C, I would like to do it a little less (say 57C)because the loin chops I use are so lean. What would you recommend. Thanks.

Merridith,
sorry for not having answered sooner.
It is my personal experience with pork tenderlon and pork neck that they need a lower core temperature than beef tenderloin or prime rib or lamb racks to give the same feeling of medium-rare; one might expect it to be the other way round, but that's just my experience.
A 15cm thick slab would be a mighty piece of roast, so I assume you mean 15mm thick, which heats from 3°C to 55°C in 18 minutes (Douglas Baldwin's table 2.3). Assuming "10cm chops" is 10mm, it would need only 8 minutes.
And yes, I do not cook tender meat longer than 4-6 hours.

Another question: Would the Thermapen or other thermocouple type digital IR thermometer be acceptable for calibration? I have, by the way, tested my SVS with about 4 different thermometers (including two digital IR thermometers, an old analogue IR type and a basic candy thermometer) just to see if the thermometers agree with the read-out on the SVS and the digital IR thermometers always agreed within .1C.

Thermapen http://www.thermowor..._thermapen.html is specified to be accurate within ±0.4°C; if you have 4 thermometers reading within ±0.1°C, odds are high that they are correct. (Our mathematician could tell you how high).
I assume you have read my article http://sousvide.wiki...ter_calibration
Regards
Pedro

[dougal]

Would someone explain to me what a "thermocouple IR" thermometer might be?

Infra Red provides a non-contact means of measuring temperature - which is very convenient for very high temperatures, but the actual accuracy of measurement is not very good (not least due to assumptions about the emissivity of the surfaces).

Thermocouples are sensors which produce a small voltage difference when heated.

My understanding has been that Platinum (electrical) resistance (varying with temperature) thermometers are more accurate overall (though more expensive) than thermocouples.
Hence generally, for accuracy, Pt100 is better than thermocouple, is better than IR. Specific products in specific situations are likely to be different, but as generalisations go, I think that's the way things are.



I'd be cautious about assuming that because two (or more) examples of the exact same product agree, that their reading is 'accurate'.
Consistent, certainly, but that's a rather different matter.




The current Thermapen (as linked by PedroG) is supplied with its own individual traceable-calibration certificate.
Its accuracy is quoted to be within the specified tolerance over its entire range.
It is capable of (lab) re-calibration at a chosen single temperature (like 55C).

As such, I'd say it should be very much more trustworthy than un-certificated, un-calibrated products, whether they happen to agree or not.

[PedroG]

I totally agree with dougal.
Some time ago, I tried to close my gap in education concerning temperature sensors, and it took me quite some time of googling.
Here is part of what I found:

Thermocouples:

Temperature difference between two bimetallic junctions produces a temperature-dependent voltage.

K-Type: NiCr (pos.) with Aluminium-plated nickel (neg.) -> 0°C … +760°C
J-Type: Fe (pos.) with Constantan (neg.) -> 0°C … +1260°C
T-Type : Cu (pos.) with Constantan (neg.)


Thermistors (= Temperature dependent resistors = RTD =Resistance Temperature Detector):

Applied measuring voltage causes a current in the sensor which heats the sensor, so they work best with a strong circulation of the surrounding media.

PTC (= positive temperature coefficient, cold conductors)

PTCs can be made of polycrystalline Titanat-ceramics like BaTiO3, with doting atoms, or of pure metals, typically Platinum.

Pt100 has 100Ω at 0°C -> -200°C … +1562°C
Pt1000 has 1000 Ω at 0°C

NTC (= negative temperature coefficient, hot conductors)

Made of Fe2O3, ZnTiO4, MgCr2O4 semiconductor materials.

NTC 10 has 10k Ω at 25°C
NTC 20 has 20k Ω at 25°C
NTC 30 has 30k Ω at 25°C
NTC 50 has 50k Ω at 25°C
NTCs often are defined at 20°C (R20)

The New Splash-Proof Super-Fast Thermapen™ is a K-type thermocouple, NIST-calibrated to ±0.4°C. Beware, it has a trim potentiometer, so you can destroy the factory-calibration.
My Greisinger GMH-3710 high precision thermometer http://www.greisinge...hp?task=2&wg=26 (accurate to ±0.03°C) has a Pt100 thermistor.
The PID-controllers from FreshMealsSolutions and Auber Instruments have NTC 50 thermistors.
Generally, thermocouples are faster and thermistors are more accurate.

@Merridith:
What did you mean by "Thermapen or other thermocouple type digital IR thermometer" ? The Combo Thermometer
IR + Fold out Probe http://www.thermowor...hermometer.html ? This would be accurate to ±1°C only.

[Paul Kierstead]

I did different types of salmon as well as chilian sea bass at 60.5c timed to hit pasteurization.

The wild coho tonight came out horrible dry. The seas bass was ok, other types of salmonnas well.

I've tried a few varieties of fish and, strictly IMO, a few degrees can make a pretty big difference in fish. For example, for the Mahi-mahi I was cooking, 60C was relatively dry but 58C was quite nice; both were unseared. From my general experience with fish, I'd say 60.5 + sear would make most varieties fairly dry ( don't know if you seared or not) and 60.5 without sear would make some fairly dry and leave others ok. I don't think you need a large movement in temperature to get significantly improved results.

[Phaz]

Another thing to mention with thermocouples is that the resolution of the device reading the voltage matters a lot. A 12 bit analog to digital converter is going to give much less accuracy than a 16 or 21 bit converter.

Another issue with thermocouples is that the relationship between voltage and temp isn't constant, it's a very non-linear curve. That introduces some error as well since the curve is estimated using a series of polynomials (sometimes up to 8 or 9 degrees). Because of this, they can also be more accurate at a given temperature than another. You can still get really good accuracy, but you have to know what you are working with.

The place I work basically makes the devices that read in the temps from thermocouples (and a number of other devices). I'm currently working on a fancy temp reader for my own experiments that I plan on testing in the SVS. Think of it like a probe that takes readings along the length of the probe instead of just the tip, so you read out a gradient of temperature rather than just the point where the probe happens to be stuck into (and if wanted log that data over time).

[Okanagancook]

I just got my Polyscience sous vide equipment but have a question about mounting the circulating pump on the plastic bath container. If I mount the pump so its side bolts rest on top of the cover of the bath then the attachment screw at the back has only part of the rim to latch onto. In addition, it is hard to get the lid off the insert food. First Picture. When I operate the equipment like this there is a large amount of steam that comes up and condenses on the front of the circulator as well as on the back near the power plug.

If I mount it underneath, see next picture, then I have a firm place for the screw to latch onto the bath but the circulator seems lower yet near the water and it is hard to get the lid to slide out.


Iam I missing something or should I just operate the thing with the lid off......does that cause too much temperature fluctuation?
Help!

Attached Images

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[jk1002]

I don't have the lid but from my experience there is no need to cover the bath unless you run it for many hours. For things that just take an hour or two I don't bother, for ribs or flanksteaks that take 24 hours and more I use plastic foil to cover.

There was a test on sousvidecooking.org that showed that an uncovered bath needs more energie. Based on my experience it doesn't affect the temperature stability and it shouldn't since it's circulating. You definitely loose a lot of water if you run long time without a cover that is the main reason for me to cover my bath but again this is not so noticeable if you run it for an hournor two.

I am worried about condensation as well, I do think the circulator is designed to hold up to it - I would avoid it though and do believe they way you positioned the cidrculator a bit higher up is ok, should be 1/3rd of an inch difference, correct?

[Okanagancook]

jk1002, thanks for your help. The difference in positions is about 3/4 of an inch. I'll run mine mostly with the lid off because the condensation on the power outlet was my biggest concern. Then for longer times, the hand made cover seems like a safer idea.
cheers

[gali]

Hello everyone. Long-time reader, learner and fan -- first post. Thought I'd post this on the sous vide thread since it has some interesting things in common.

Has anyone ever heard of this type of cold pressure sterilization? From this producer of refrigerated foods: http://www.sandridge...News.7.48.lasso

Most processed foods today are heat treated to kill bacteria and have preservatives added to extend shelf life, which often diminishes product quality and taste. HPP provides an alternative means of killing bacteria that can cause spoilage or food-borne disease without a loss of sensory quality or nutrients.

In the HPP process, the product is packaged in a flexible container and is loaded into a high pressure chamber filled with cold water and then pressurized with a pump. An equal amount of pressure is transmitted through the package into the food itself. Pressure is applied for a specific time, usually three to five minutes. Because the pressure is transmitted uniformly (in all directions simultaneously), food retains its shape, even at extreme pressures, and because no heat is needed, the sensory characteristics of the food are retained while still destroying the harmful bacteria. Bacteria are inactivated at levels of 58,000-87,000 psi and water temperatures of less than 45 degrees Fahrenheit. These pressure levels retain all the taste, texture and integrity of the original food ingredients without the need for preservatives and/or heat processing.

[PedroG]

I don't have the lid but from my experience there is no need to cover the bath unless you run it for many hours. For things that just take an hour or two I don't bother, for ribs or flanksteaks that take 24 hours and more I use plastic foil to cover.

There was a test on sousvidecooking.org that showed that an uncovered bath needs more energie. Based on my experience it doesn't affect the temperature stability and it shouldn't since it's circulating. You definitely loose a lot of water if you run long time without a cover that is the main reason for me to cover my bath but again this is not so noticeable if you run it for an hournor two.

I am worried about condensation as well, I do think the circulator is designed to hold up to it - I would avoid it though and do believe they way you positioned the cidrculator a bit higher up is ok, should be 1/3rd of an inch difference, correct?

jk1002, thanks for your help. The difference in positions is about 3/4 of an inch. I'll run mine mostly with the lid off because the condensation on the power outlet was my biggest concern. Then for longer times, the hand made cover seems like a safer idea.
cheers

jk1002:
I did not find Jean-François' test on sousvidecooking.org, would you mind posting a permalink?

Okanagancook:
Julabo offers floating hollow plastic balls, see http://www.julabo.de...ads/8970010.pdf for covering sous vide baths, but you have to order 1000 pcs.; I use ping-pong-balls instead to cover the water surface. Spheres ideally cover 90.7% (i.e. the area of a circle divided by it's surrounding hexagon) of the water surface, substantially reducing heat loss and evaporation.
My VEGA stockpot (9L 400W side-heater, controlled by a SousVideMagic 1500B) covered with the original sheet metal lid consumes about 54W in steady state at 55°C; with ping-pong-balls instead of the lid, power consumption is reduced to 43W.
I also have a FreshMealsMagic (controlled by a SousVideMagic 1500D) with a 18L polycarbonate pot; filled with 13L water and covered with ping-pong-balls, it consumes 116W in steady state at 55°C; insulated with a triple layer of bubble wrap plus a cover made up of four layers of bubble wrap sealed in a vacuum pouch and floating on top of the ping-pong-balls, power consumption is reduced to 42W.

Using plastic spheres instead of a lid allows for easy insertion and retrieval of food pouches, especially when they are suspended on a skewer to keep them in a vertical position, and with your IC it should also avoid condensation on the power outlet.

[jk1002]

Article

Hi, here is the link to the sousvidecooking.org article

[MartinH]

Hi Gali,

Those pressures are huge considering that surface air pressure is about 14 psi, or an hydraulic system is a couple of thousand psi, or the bottom of the deepest sea trench is around 16,000 psi (if I recall correctly). I'm amazed the food is not altered. I'm also intrigued to know how they generate such force.

Has anyone ever heard of this type of cold pressure sterilization? From this producer of refrigerated foods: http://www.sandridge...News.7.48.lasso

Bacteria are inactivated at levels of 58,000-87,000 psi and water temperatures of less than 45 degrees Fahrenheit. These pressure levels retain all the taste, texture and integrity of the original food ingredients without the need for preservatives and/or heat processing.

[nickrey]

See this link for some more information on high pressure processing and how it works.

[dougal]

... I use ping-pong-balls instead to cover the water surface. Spheres ideally cover 90.7% (i.e. the area of a circle divided by it's surrounding hexagon) of the water surface, substantially reducing heat loss and evaporation.
...

Aaaah, but that number would refer to the ideal situation where the sphere floats 50% submerged.
Ping-pong balls float much higher than that, and so the reduction in free surface is very much less.
But they will also tend to act as condensers, further reducing evaporation.


A metal lid (ideally with a good heat sink) acts as an even better condenser. Think tagine! (Or le Creuset Doufeu.)


Maybe its also worth mentioning that cheap all-silicone flexible baking sheets are not hard to cut and safe to oven temperatures. Thus they can make a nice material for conformable seals ...

[gali]

Those pressures are huge considering that surface air pressure is about 14 psi, or an hydraulic system is a couple of thousand psi, or the bottom of the deepest sea trench is around 16,000 psi (if I recall correctly). I'm amazed the food is not altered. I'm also intrigued to know how they generate such force.

Nick's link is very good. Originally I thought it worked like chamber vacuum sealer, the pressure is applied both inside and outside of the "bag" before sealing so the food doesn't get completely crushed - which was why I posted here. Plus I wanted to see who here would build the first home unit.

[Rebecca Dalton]

I have a couple of 1" grass-fed ribeye steaks with bone that I would like to cook sv for later today. I need a recommendation re: docking the meat or not, including a fat in the vac bag to compensate for minimal marble, and suggested time/temp for medium-rare. Thanks.

Edited by Rebecca Dalton, 01 May 2010 - 08:59 AM.

[Okanagancook]

PedroG
Thanks for the alternatives to covering the bath with the provided lid. I'll have to experiment and also find a place in my small town that stocks that many ping pong balls