Sous Vide: Recipes, Techniques & Equipment, 2011

[paulpegg]

I have never tried to sv ground meat. Jason Logsdon, in his book "Beginning Sous Vide" has a listing for Hamburger at 55C for 2-4 hours. My own thought would be to sv the whole pieces and grind them up just before forming into a patty. This would at least give the meat some color but it would probably not bind together as well as raw ground meat patties.

[Robert Jueneman]

C. bot toxin (which is the danger) is broken down by fairly gentle heat. (The spores produce the toxin, which is why spores need to be considered, but its the toxin that is the actual danger.)

Expect something like a 100x reduction in toxicity with every 30 minutes at 56C (133F) ...

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4700984

so 10,000x (10^4) after 1 hour, 1,000,000x (10^6) after 1 hour 30, 100,000,000x (10^8) after 2 hours and so on.

Re-pasteurising should be effective against C. bot toxin. (If there was any there with your nitrite and salt.)

But you do need pressure-cooker temperatures 120C+ (250F+) to hurt the spores themselves ...

Is C. perf very different?

This has been a fascinating and very enlightening thread, and I'd like to summarize what I've taken from it, vis a vis the food safety issues:

1. Pasteurizing beef at 131F/55C or higher kills (and keeps killing) all of the vegetative pathogens, so cooking/holding meat at that temperature is safe, virtually forever, although you don't want to overdo it, especially with cuts that are relatively tender to begin with. (We are primarily talking about beef here, and not poultry, and certainly not fish.)

2. Pasteurization does NOT kill the spores of certain harmful bacteria, such as C bot. So reducing the temperature after pasteurization to below 55C would allow those spores to germinate relatively rapidly. In the process, and especially in an anaerobic environment, potentially deadly neurotoxins could be produced.

3. Re-pasteurization at the end of such a process would again kill off any of the bacteria that had germinated from the spores.

4. Fortunately, those same neurotoxins (at least those from C. bot.) are broken down by heat, achieving an 8D reduction after 2 hours at 55C. So IF you re-pasteurized completely, as with Kenneth's pastrami-left-in-the-sink case, you are most likely safe, even disregarding things like nitrates, salt, and pH. However, this is a pretty tortuous and convoluted argument, and I would hate to think that we had overlooked something in the process. So I can't recommend that approach.

5. In any case, just because it doesn't kill you doesn't mean that the end result is going to taste or smell good. In particular, lactic acid build-up may not be harmful, but I wouldn't want to eat the results. Other possible decomposition (AKA spoilage) by-products could also exist.

6. The reason for proposing this not-very-well-thought-out violation of the standard cook-chill rules was an attempt to SV a relatively tough cut of meat, such as chuck, to make it as tender a possible, while still maintaining a rare degree of doneness. But it appears that the enzymes which help to age and thereby tenderize beef muscle operate at their maximum efficiency at around 120F/48C, and slowly become denatured at higher temperatures, thereby ceasing to be effective any more. So pasteurizing first, and then holding the meat at a lower temperature, as I had proposed, wouldn't do any good from a tenderizing perspective, over and above the complex food safety issues.

7. However, doing it the other way around, with a multi-stage heating approach as suggested in MC, does seem to make sense. The idea here is to SV the meat at around 120F/48C for four hours to promote maximum enzymatic action, and then to increase the temperature to 131F/55C and cook it for as long as seems necessary -- probably 20-24 hours in the case of chuck, or even 48-72 hours for brisket or short ribs, in order to slowly convert the collagen into gelatin -- a process that is primarily controlled by heat and time.

8. If for some reason the meat is not consumed immediately afterwards, either because you were preparing for later reheating, or because there were leftovers, the standard ice-bath discipline should be used to lower the temperature as quickly as possible, to below 4C. This is particularly important in the case of food that has not be exposed to oxygen, because C. bot is an anaerobic bacterium, and can germinate and produce neurotoxins while still sealed in the bag, unless the temperature is reduced to the point where their multiple rate becomes negligible.

Did I miss anything?

[Robert Jueneman]

I have never tried to sv ground meat. Jason Logsdon, in his book "Beginning Sous Vide" has a listing for Hamburger at 55C for 2-4 hours. My own thought would be to sv the whole pieces and grind them up just before forming into a patty. This would at least give the meat some color but it would probably not bind together as well as raw ground meat patties.

I don't eat a lot of hamburger, but I have prepared them SV, and would certainly do so for anyone who might be immune compromised, pregnant, etc.

Form nice big thick 1" patties however you'd like, including seasoning, onions, etc. SV them at 131F/55C for two hours to pasteurize them. Then post-sear on a very hot grill, or in a cast iron skillet that is smoking hot, to get the Maillard reaction and the outer char, while still keeping the inside a nice medium rare.

If you aren't concerned about pasteurization, then SV them for a couple of hours at 125F/50C , and then sear as above for a deliciously rare interior.

Sure beats all that crazy flipping, constantly watching, never quite knowing the right temperature on the grill, etc.

And if you are cooking for a crowd, or on a picnic, it's even easier -- just package the pre-seasoned hamburgers four to a gallon FoodSaver bag, fill up a beer cooler with hot water, throw the bag in the hot water and drive off. When you get there, fire up the portable grill, throw the burgers on the grill and/or fan them with a torch, and pass the ketchup and mustard!

If you have two coolers, fill one with hotter water (150F), bag up some corn on the cob with butter, lime juice, and chipotle, and throw those in the hot water for 30 minutes. Char briefly on the grill later, if you like.

And if you have three coolers -- well, it is a BEER cooler, isn't it?

:-)

[Chris Amirault]

Don't vacuum seal them, though, as they get rubbery. Just put 'em in a Ziplok bag and push the air out by submerging them in water.

[KennethT]

Bob - thanks for your summary!

So, I didn't get even remotely sick from my initial portion of the pastrami, and since my sample portion was over double the size of the portion I was giving to guests, I assumed it would be ok. Everyone loved it by the way - the flavor was great, with the smoke really coming through even though I only smoked it for 30 minutes or so in my stovetop smoker. I originally commented that the cheeks were a bit dry in my sample taste, but when slicing for the guests, I noticed it was much more gelatinous and juicy - it was really excellent.

[e_monster]

Hi Bob,

I think the focus on only the anerobic bacteria and their neurotoxins may be slightly misplaced--especially as relates to the prepration that you initially proposed, (pasteurizing at 131F and then lowering to 120F for a long period), I would be worried about bugs like e. coli, too. -- especially since you are incubating for a long time. If there are any small holes in the meat, you may get transmission of the spores to the interior of the meat where they may germinate and where they will be safe when you sear. My concern is that once cooked in the bag, you have a lot of free liquid in the bag that can serve as a vector of transportation -- so that spores can more easily relocate (something that won't happen if the meat is cooked in an oven outside of a bag).

It just seems like an iffy proposition to me to have spores incubating that long. It should also be remembered that pasteurization may not even eliminate all of the living pathogens (especially if there were any holes in the meat) -- it simply reduces the amount to an amount of pathogens to a level that is safe if the meat is consumed on a timely basis. Since you are following the pasteurization by a possible incubation period, you have a somewhat less known state after your 120F cooking than you would otherwise.

Anyway, that is my thought.

--E

C. bot toxin (which is the danger) is broken down by fairly gentle heat. (The spores produce the toxin, which is why spores need to be considered, but its the toxin that is the actual danger.)

Expect something like a 100x reduction in toxicity with every 30 minutes at 56C (133F) ...

http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=4700984

so 10,000x (10^4) after 1 hour, 1,000,000x (10^6) after 1 hour 30, 100,000,000x (10^8) after 2 hours and so on.

Re-pasteurising should be effective against C. bot toxin. (If there was any there with your nitrite and salt.)

But you do need pressure-cooker temperatures 120C+ (250F+) to hurt the spores themselves ...

Is C. perf very different?

This has been a fascinating and very enlightening thread, and I'd like to summarize what I've taken from it, vis a vis the food safety issues:

1. Pasteurizing beef at 131F/55C or higher kills (and keeps killing) all of the vegetative pathogens, so cooking/holding meat at that temperature is safe, virtually forever, although you don't want to overdo it, especially with cuts that are relatively tender to begin with. (We are primarily talking about beef here, and not poultry, and certainly not fish.)

2. Pasteurization does NOT kill the spores of certain harmful bacteria, such as C bot. So reducing the temperature after pasteurization to below 55C would allow those spores to germinate relatively rapidly. In the process, and especially in an anaerobic environment, potentially deadly neurotoxins could be produced.

3. Re-pasteurization at the end of such a process would again kill off any of the bacteria that had germinated from the spores.

4. Fortunately, those same neurotoxins (at least those from C. bot.) are broken down by heat, achieving an 8D reduction after 2 hours at 55C. So IF you re-pasteurized completely, as with Kenneth's pastrami-left-in-the-sink case, you are most likely safe, even disregarding things like nitrates, salt, and pH. However, this is a pretty tortuous and convoluted argument, and I would hate to think that we had overlooked something in the process. So I can't recommend that approach.

5. In any case, just because it doesn't kill you doesn't mean that the end result is going to taste or smell good. In particular, lactic acid build-up may not be harmful, but I wouldn't want to eat the results. Other possible decomposition (AKA spoilage) by-products could also exist.

6. The reason for proposing this not-very-well-thought-out violation of the standard cook-chill rules was an attempt to SV a relatively tough cut of meat, such as chuck, to make it as tender a possible, while still maintaining a rare degree of doneness. But it appears that the enzymes which help to age and thereby tenderize beef muscle operate at their maximum efficiency at around 120F/48C, and slowly become denatured at higher temperatures, thereby ceasing to be effective any more. So pasteurizing first, and then holding the meat at a lower temperature, as I had proposed, wouldn't do any good from a tenderizing perspective, over and above the complex food safety issues.

7. However, doing it the other way around, with a multi-stage heating approach as suggested in MC, does seem to make sense. The idea here is to SV the meat at around 120F/48C for four hours to promote maximum enzymatic action, and then to increase the temperature to 131F/55C and cook it for as long as seems necessary -- probably 20-24 hours in the case of chuck, or even 48-72 hours for brisket or short ribs, in order to slowly convert the collagen into gelatin -- a process that is primarily controlled by heat and time.

8. If for some reason the meat is not consumed immediately afterwards, either because you were preparing for later reheating, or because there were leftovers, the standard ice-bath discipline should be used to lower the temperature as quickly as possible, to below 4C. This is particularly important in the case of food that has not be exposed to oxygen, because C. bot is an anaerobic bacterium, and can germinate and produce neurotoxins while still sealed in the bag, unless the temperature is reduced to the point where their multiple rate becomes negligible.

Did I miss anything?

[Robert Jueneman]

Don't vacuum seal them, though, as they get rubbery. Just put 'em in a Ziplok bag and push the air out by submerging them in water.

The proper vacuum setting for various kinds of SV cooking is certainly one of the more contentious issues around, ranging from "just suck the air out of a Ziploc with a straw" to "use a chamber vacuum set at 99.9% plus 30 seconds for everything." Some people say that fish turns mushy under a hard vacuum, and others saying that fish normally experience much higher pressures when swimming than atmospheric pressure could possibly induce, and so this doesn't make any sense.

The problem becomes even more complex when you consider the optimum conditions for long-term frozen storage, vs. simply cooking a meal, at least for those of us who would like to take a pre-sealed bag out of the freezer and throw it in the water bath, without having to mess with it again.

Blackp and I tried to replicate Dave Arnold's finding that a hard vacuum causes dryness, but were unable to confirm the effect -- at least with chicken. And at least with my chicken tenders, the hard vacuum lost 2% LESS in turns of meat juices than the softer vacuum versions. Go figure.

As I say, I don't cook hamburgers SV that often, and so I can neither confirm nor deny Chris' claim that a harder vacuum makes the hamburger rubbery.

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

Can anyone else confirm or deny this?

[MartinH]

A couple of thoughts on hamburgering:

A 1" thick patty would take about half an hour to come to 55C in the middle.

A gas grill gives off quite a lot less heat than a charcoal grill (or a hot cast iron pan) - using a gas grill risks either underbrowing the surface or overcooking the innards. After frustrations with using my grill, I'm now a strong believer in the double attack strategy: flop the meat on the grill and simultaneously ignite a torch for some flamethrower action. (Applies not just to hamburgers of course.)

I think the ziplok bag idea (rather than vacuum sealing) is so that the patty isn't compressed too much, but that depends too on not squishing the patty too much when you form it.

I don't have Modernist Cuisine to hand, but I recall a hamburger recipe which went: SV, dip in liquid nitrogen to freeze the surface, deep fry in very hot oil to brown.

[jmolinari]

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

Can anyone else confirm or deny this?

I think this makes perfect sense from a theoretical perspective. A hamburger should be loosely held together when carefully formed and has air pockets between the strands of meat. Put it under vacuum and you make a sense puck out of it that won't crumble the same way a loose patty will. I'm sure the myocin protein has something to do with that as well. There is more meat to meat contact so the protein binds more of the meat strands together.

[e_monster]

For what its worth, I have made a lot of hamburgers sous-vide using both my FoodSaver and a ziploc with the air evacuated by water dunking and the results (when served to people who did not know how the meat had been prepared). With the FoodSaver, I pay a bit of attention so that things don't get squeezed too much (I don't know if that is actually necessary, though) and people universally say that they are the best juiciest burgers they have had. I usually make fairly thick patties and cook at 132F till pasteurized and then sear with either my Iwatani torch or in a super hot skillet to create a nice crust. The interior is a nice red/pink and there is nothing chewy about the burgers.

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

Can anyone else confirm or deny this?

I think this makes perfect sense from a theoretical perspective. A hamburger should be loosely held together when carefully formed and has air pockets between the strands of meat. Put it under vacuum and you make a sense puck out of it that won't crumble the same way a loose patty will. I'm sure the myocin protein has something to do with that as well. There is more meat to meat contact so the protein binds more of the meat strands together.

[Robert Jueneman]

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

Can anyone else confirm or deny this?

I think this makes perfect sense from a theoretical perspective. A hamburger should be loosely held together when carefully formed and has air pockets between the strands of meat. Put it under vacuum and you make a sense puck out of it that won't crumble the same way a loose patty will. I'm sure the myocin protein has something to do with that as well. There is more meat to meat contact so the protein binds more of the meat strands together.

Kenji Lopez-Alt also uses the Ziplock technique, FWIW. Cf. http://www.seriouseats.com/recipes/2010/06/sous-vide-burgers-recipe.html

On the other hand, there is an interesting post at http://www.fiftyfourdegrees.com/lang/en-us/archives/370, wherein he was careful to chill the burger before sealing it, so that it would hold its shape.

If the patty is nearly frozen before being sealed, it would seem that the "hockey puck" compression effect would be minimized. Now, whether that would minimize the "rubbery" texture Chris talks about, I don't yet know. Yet another variable to consider.

Finally, see http://blog.ideasinfood.com/ideas_in_food/2010/06/the-meat-grinder.html for a discussion about freshly ground beef vs. beef that has oxidized in the refrigerator overnight.

Hey guys, this isn't Neanderthal-style cooking we're talking about here - this is about physics, and chemistry, even if it's in a beer cooler!

Bob

[Chris Amirault]

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

I think this makes perfect sense from a theoretical perspective. A hamburger should be loosely held together when carefully formed and has air pockets between the strands of meat. Put it under vacuum and you make a sense puck out of it that won't crumble the same way a loose patty will. I'm sure the myocin protein has something to do with that as well. There is more meat to meat contact so the protein binds more of the meat strands together.

My guess is: what Jason said.

I can't confirm with double-blind anything, but if you had had the burgers I sealed to 99% using my spiffy new chamber sealer, well, you'd have no need for blindfolds. Same meat, same patty formations, same temps, same time: the four additional burgers I made using the Ziplok method were perfect (yes, best burgers ever, all that), whereas the four that were chamber sealed literally bounced when I dropped them on the counter.

[Robert Jueneman]

But I would like to see some double-blind tests done, before this bit of possible folklore gets enshrined. Maybe his results were due to a particular grind, etc., or maybe he discovered a Higgs boson, or whatever, but so far I don't understand the food science behind rubbery hamburgers and a hard vacuum.

I think this makes perfect sense from a theoretical perspective. A hamburger should be loosely held together when carefully formed and has air pockets between the strands of meat. Put it under vacuum and you make a sense puck out of it that won't crumble the same way a loose patty will. I'm sure the myocin protein has something to do with that as well. There is more meat to meat contact so the protein binds more of the meat strands together.

My guess is: what Jason said.

I can't confirm with double-blind anything, but if you had had the burgers I sealed to 99% using my spiffy new chamber sealer, well, you'd have no need for blindfolds. Same meat, same patty formations, same temps, same time: the four additional burgers I made using the Ziplok method were perfect (yes, best burgers ever, all that), whereas the four that were chamber sealed literally bounced when I dropped them on the counter.

Interesting. And more from Kenji Lopez-Alt, talking about the Heston Blumenthal In Search of Perfection Hamburger, at http://aht.seriouseats.com/archives/2008/05/the-blumenburger-the-most-laborintensive-hamburger-in-the-world.html:

"And finally, as for the meat: When meat is ground and salted, the salt and the mechanical action of grinding will cause some of the proteins in the meat (myosin, in particular) to denature and eventual link up with each other. The more you 'mush' the meat together, the more tangled up the myosin strands get, and the denser and rubbier your patty becomes. When you put meat through the small plate of a meat grinder, the long fibrils in the meat get cut into pieces that are at most the width and length of the plate (which in this case is 3mm) - small enough that it's not going to cause a sensation of toughness. What will cause toughness, however, is the relinking of myosin proteins after the meat has been ground.

"That's why most good hamburger recipes where tenderness and open texture are key advise you to touch the meat as little as possible after grinding. What Heston is playing off of in his recipe is the fact that when meat is forced through the holes on the plate of a meat grinder, those myosin proteins are linking up with each other into long strands - strands which are tougher to bite through widthwise than they are to separate from each other lengthwise.

"It's an interesting idea, but I don't think it really worked. I make burgers in which I nearly freeze the meat before grinding (cold proteins are less likely to denature and link up), and I think the burgers I get using that method are more tender than these ones were, even without the 'pain in the ass' aligning of ground meat strands."

So nearly freezing the burgers before sealing them seems like a good idea, as does minimal compression and handling, and doing everything with meat that you grind yourself (preferably a mix of chuck, brisket, and dry-aged short ribs, if you can find them).

Unfortunately, this sort of goes against one of my objectives, which would be to be able to pre-package such burgers and freeze them, rather than have to go through all of this when I'm in a hurry for dinner. And certainly freezing burgers in a Ziploc bag is going to produce freezer burn in relatively short order, and undesirable oxidation as well.

Setting the chamber vacuum to a lower percentage, or stopping the FoodSaver when you start to see some compression would presumably help, but another alternative might be to use a Modified Atmosphere Packaging technique (for those with a really, really, really spiffy chamber vacuum -- one with a gas port), in which case you could suck out all of the oxygen and then introduce whatever amount of CO2 or nitrogen into the bag you choose (maybe 10-20%?) to avoid the compression factor. Of course the bags might then float, and might not get perfect contact with the water, but ...

Or you could say forget about a burger, and just eat the chuck or brisket, etc., as a steak instead. Much simpler!

[jmolinari]

What about pre-freezeing the hamburgers into solid pucks, then vac packing?

I do that with wet stuff

[HowardLi]

Put a small block of dry ice into the bag and then let the bag sit upright with most of the zipper closed. Leave a small vent. The CO2 will displace nearly all the oxygen, so once you vacuum (or water-press) the bag, whatever's left will be fairly devoid of O2.

EDIT: The CO2 sinks, so if you let the bag fall over or invert it, you will lose your precious inert purge.

Edited May 17, 2011 by HowardLi (log)

[Robert Jueneman]

Put a small block of dry ice into the bag and then let the bag sit upright with most of the zipper closed. Leave a small vent. The CO2 will displace nearly all the oxygen, so once you vacuum (or water-press) the bag, whatever's left will be fairly devoid of O2.

EDIT: The CO2 sinks, so if you let the bag fall over or invert it, you will lose your precious inert purge.

Pre-freezing the burgers seems like the way to go.

But other than the fact that I don't happen to have small blocks of dry ice just lying around in my kitchen, I have some possible concerns about using CO2.

My understanding is that it is used commercially to provide extended shelf life for say, chicken, under retail display conditions (not long-term storage).

But doesn't CO2 plus water form carbonic acid (it's been a long, long time since my last chemistry class)?

And although that might have beneficial bacteriostatic properties, do I really want carbonic acid on my burgers?

If I do go the route of adding a gas port to my Minipack chamber vacuum, I'm thinking that I would probably want to use nitrogen, rather than C02 as the filler gas.

Nathanm, you've got every appliance known to man -- do you have any thoughts on this issue?

[HowardLi]

Put a small block of dry ice into the bag and then let the bag sit upright with most of the zipper closed. Leave a small vent. The CO2 will displace nearly all the oxygen, so once you vacuum (or water-press) the bag, whatever's left will be fairly devoid of O2.

EDIT: The CO2 sinks, so if you let the bag fall over or invert it, you will lose your precious inert purge.

Pre-freezing the burgers seems like the way to go.

But other than the fact that I don't happen to have small blocks of dry ice just lying around in my kitchen, I have some possible concerns about using CO2.

My understanding is that it is used commercially to provide extended shelf life for say, chicken, under retail display conditions (not long-term storage).

But doesn't CO2 plus water form carbonic acid (it's been a long, long time since my last chemistry class)?

And although that might have beneficial bacteriostatic properties, do I really want carbonic acid on my burgers?

If I do go the route of adding a gas port to my Minipack chamber vacuum, I'm thinking that I would probably want to use nitrogen, rather than C02 as the filler gas.

Nathanm, you've got every appliance known to man -- do you have any thoughts on this issue?

I'm pretty sure you wouldn't be able to taste it - it's an extremely weak acid, significantly weaker even than acetic acid, and remember that there will not be a lot of CO2 in the package.

Anyway, you're right, nitrogen or argon would be superior to CO2. I just figured dry ice would be easier to get.

[HowardLi]

On an unrelated note, has anybody checked out this web page?

http://www.goodhousekeeping.com/product-testing/reviews-tests/kitchen-cooking/plastic-safety-heat-food-6

Looks like regular zip-top bags might be safe after all... but shame on you, Glad.

[jmolinari]

On an unrelated note, has anybody checked out this web page?

http://www.goodhousekeeping.com/product-testing/reviews-tests/kitchen-cooking/plastic-safety-heat-food-6

Looks like regular zip-top bags might be safe after all... but shame on you, Glad.

Thanks interesting, thanks, but why "shame on you, Glad" ? None of the products leached BPA or phthalates even if some had them in the materials...

[HowardLi]

On an unrelated note, has anybody checked out this web page?

http://www.goodhousekeeping.com/product-testing/reviews-tests/kitchen-cooking/plastic-safety-heat-food-6

Looks like regular zip-top bags might be safe after all... but shame on you, Glad.

Thanks interesting, thanks, but why "shame on you, Glad" ? None of the products leached BPA or phthalates even if some had them in the materials...

Is it not possible that it could leach out? Just because it doesn't happen in testing (with "food substitutes") doesn't mean that it couldn't happen in particular, untested-for situations in real life.

[jmolinari]

On an unrelated note, has anybody checked out this web page?

http://www.goodhousekeeping.com/product-testing/reviews-tests/kitchen-cooking/plastic-safety-heat-food-6

Looks like regular zip-top bags might be safe after all... but shame on you, Glad.

Thanks interesting, thanks, but why "shame on you, Glad" ? None of the products leached BPA or phthalates even if some had them in the materials...

Is it not possible that it could leach out? Just because it doesn't happen in testing (with "food substitutes") doesn't mean that it couldn't happen in particular, untested-for situations in real life.

True, good point...

[rotuts]

things may or may not be a certain way on these chemicals

but why take the chance if you dont have to when there are alternatives?

afterall what was considered safe not so long ago isnt necessarily considered safe now.

[jmolinari]

Rotuts, yep...i buy BPA free stuff when possible,

[HowardLi]

I did some burgers at 145 F today (~63C). Can anybody explain why they came out totally gray, with no hint of pink?

[PedroG]

I did some burgers at 145 F today (~63C). Can anybody explain why they came out totally gray, with no hint of pink?

See Harold McGee, On Food and Cooking, p. 152: at 145-155°F (Medium-well) "Pink fades to gray-brown".

Nathan Myhrvold in Modernist Cuisine, p. 3•86 and 3•234, recommends 52-56°C (126-133°F) for hamburgers.

How accurate (accuracy, not resolution of the display!) is your temperature control? Is your reference thermometer NIST-calibrated? Some SV-rigs have been reported to be several degrees off ex factory.

How long was your SV-cooking time? Post-searing method/temperature/time?