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Sous vide and frozen meat

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#1 TdeV

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Posted 30 November 2013 - 12:41 PM

I notice that D. Baldwin says that one can reheat frozen cooked sous vide meat in a one hour waterbath, so that makes me think that frozen meat unfreezes quickly.

 

Lots of the meat which I will eventually cook sous vide is now sitting in the freezer vacuum-sealed in cook-safe bags.

 

Can I put the frozen meat directly into a water bath and just extend the cooking time? Or is this a really dumb idea?



#2 gfweb

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Posted 30 November 2013 - 12:45 PM

This a good idea. Fast thaw and a speedy passage thru the danger zone.

#3 FeChef

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Posted 30 November 2013 - 12:52 PM

I do it with raw frozen hamburger patties. But they are very thin so they reach pastuerization temp in 1-2 hours. But to answer your question, it is safe as long as the meat reaches 131.5F in 4 hours according to Baldwin. This is red meats. Im not sure about poultry though. I have a turkey breast loaf cooked to 146F frozen in my freezer. It took 4 hours to reach 130F and 8 hours to reach 146F. Someone told me it was safe to eat but im still debating if i want to test it. I hate to waist a good 8/lb turkey breast loaf.



#4 Shalmanese

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Posted 30 November 2013 - 02:39 PM

By the laws of physics, putting frozen food in a properly controlled water bath cannot be slower than any room temperature method of defrosting. Think about it, by the time the center is 4C, the outside is already 50+C and transmitting heat so the center is going to get to pasteurization temps faster. Thus, from a food safety perspective, anything that's safe for defrosted food is also safe for frozen food.

 

The only concern is if your heating element is inadequate and you put in enough frozen food to bring the water bath temperature down to unsafe temperatures for too long but this can easily be detected and fixed.


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#5 TdeV

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Posted 30 November 2013 - 02:58 PM

Thanks, Shalmanese. I guess I could afford to start with hotter water then? I.e. if my long cook temp is 140C, then I should be able to start with 160C water, right?

 

Wait. I've just figured out how silly this is, my heating element won't turn on until the temp falls below 140C. :blush:


Edited by TdeV, 30 November 2013 - 03:21 PM.


#6 Ozcook

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Posted 30 November 2013 - 03:30 PM

I thaw, or cook from frozen, all the time. I've only ever had a problem once. I left some lamb rumps that were already close to use by date - and which were subsequently frozen because I was going overseas - in the SV for twice the normal cooking time. They tasted okay, but the texture was so spongy as to be off-putting. In all other cases I can't spot the difference.

 

I put the frozen meat/fish/poultry into the SV at the temp I want the food cooked at. There can be a drop of 5F or so when first put into the SV, but that lasts about 5 minutes max.

 

So if I wanted my food cooked at 140F that's what I would set the SV for, certainly not anything higher, much less 160.


Edited by Ozcook, 30 November 2013 - 03:32 PM.

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#7 dcarch

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Posted 30 November 2013 - 03:43 PM

I have sous vided many times the entire frozen 18-20 lb turkey.

 

There is only one problem doing it this way, can you guess? 

 

The giblets in that paper bag will be cooked inside the turkey.

 

 

dcarch


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#8 nickrey

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Posted 30 November 2013 - 07:47 PM

Thanks, Shalmanese. I guess I could afford to start with hotter water then? I.e. if my long cook temp is 140C, then I should be able to start with 160C water, right?
 
Wait. I've just figured out how silly this is, my heating element won't turn on until the temp falls below 140C. :blush:

This is not as silly as you think. The frozen meat will cool the water when it is added. It is also phase shifting from frozen to thawed so it will have a larger effect than would be predicted simply adding the masses and temperatures. I start off with water warmer than my target temperature then monitor the temperature after the food is added. As it drops below target temperature, which it will, I add more hot water to bring it back up. I do this by scooping out some of the water and replacing it with hot water. Once it reaches equilibrium, I leave it to heat through and then treat it as for normal sous vide cooked food.

I far prefer this method of cooking to thawing in the refrigerator and then reheating. The thermal conductivity of water means that it passes quickly through the danger zone. Moreover, it is very convenient.

Edited to add: I just converted your temperatures to Celsius and your temperatures are way too high. I wouldn't reheat pre-cooked food in a water bath anything above 57C (135F). You're only reheating it, not cooking from scratch.

Edited by nickrey, 30 November 2013 - 07:52 PM.

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#9 Shalmanese

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Posted 30 November 2013 - 10:26 PM

Thanks, Shalmanese. I guess I could afford to start with hotter water then? I.e. if my long cook temp is 140C, then I should be able to start with 160C water, right?

 

Wait. I've just figured out how silly this is, my heating element won't turn on until the temp falls below 140C. :blush:

 

The problem is not during the first few moments of cooking, it's if your bath is struggling to keep up for hours on end. This is really only an issue if your bath size is on the upper end of what your heating element can accommodate *and* you overfill your bath with food. Keep both the bath size and food:water ratio sane and you shouldn't have to worry.

 

I actually do the opposite and just throw the food into the room temp bath as soon as it's turned on and let it come up to temp as it's defrosting. This is largely because I'm impatient and want the food reheated as fast as possible.


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#10 weedy

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Posted 30 November 2013 - 11:24 PM

 

 

 

I actually do the opposite and just throw the food into the room temp bath as soon as it's turned on and let it come up to temp as it's defrosting. This is largely because I'm impatient and want the food reheated as fast as possible.

 

I basically do the same, but fill the bath with hot water.

Why NOT give it a head start?


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#11 pbear

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Posted 01 December 2013 - 12:13 AM

TdeV:  I think you're misreading Baldwin.  Table 2.3 of his Practical Guide gives heating times from frozen and, while some are under an hour, most are more (how much more depending on shape and thickness).  I don't have any experience with the question you're asking, as I never cook from frozen, but this table would give me pause.  I'd fear the outside would be overcooked getting the core to temp and holding it there long enough to pasteurize.  This probably isn't a problem for long-cooked braising cuts, but could be for tender ones (especially something thick, like a turkey breast or beef roast).  Also, if there are pasteurization tables for cooking from frozen, I don't recall having seen them.  Perhaps you could back into the calculation by tacking together Table 2.3 and the pasteurization times from the regular tables, using the minimums as the core presumably is already at temp, but that seems a bit ad hoc.  Rather, I'd defrost conventionally (which keeps the meat cool) and cook from 41F as the standard pasteurization tables assume.

 

FeChef:  That would be me.  FWIW, the four hour rule I mentioned in the earlier conversation comes in Baldwin in the text following Table 2.3.  To understand why this works, review his discussion of food safety (earlier in the Guide).  There, he explains, "Most food pathogens stop growing by 122°F (50°C), but the common food pathogen Clostridium perfringens can grow at up to 126.1°F (52.3°C). So in sous vide cooking, you usually cook at 130°F (54.4°C) or higher."  Notably, of itself, reaching temp only stops further reproduction of the pathogens.  To reduce them to safe levels, i.e., to pastueurize, the meat must be held at temp for the times given in the pasteurization tables.  As I recall, you did that, which is why I said you're good to go.  But, of course, only you can decide whether you're comfortable doing so.



#12 rotuts

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Posted 01 December 2013 - 05:34 AM

I do this all the time.  sometimes I dont have enough turkey dark meat for a 'full bath'  ie 12 - 14 packages so these I freeze and label as such.

 

when I get enough  ( i use a large beer cooler for these longer cooks ) i use hot water to get the bath started, then add the fz legs/thighs

 

some times while the bath is getting to temp I put the tzhe dark meat in pots of hot tap water first to get them going

 

10 - 20 minutes then into the bath this keeps the bath water from dropping too low.  never do I use a bath water temp above the target temp for the cooking item.  makes no sense to me

 

works fine.



#13 DiggingDogFarm

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Posted 01 December 2013 - 05:46 AM

Douglas Baldwin on pasteurizing from frozen......

 

http://forums.egulle...11#entry1802737


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#14 nickrey

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Posted 01 December 2013 - 05:49 AM

Agree with all that is said on cooking from frozen. Water is a great conductive medium and the meat defrosts very quickly. If you're using your final temperature or a few degrees above, I can't see how you'd overcook the outside of the meat. Use Douglas's tables or those in sous vide dash and you will be fine.


Edited by nickrey, 01 December 2013 - 05:55 AM.

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#15 FeChef

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Posted 01 December 2013 - 09:16 AM

Someone mentioned it being safer to thaw in the heated water bath because its quicker but i disagree. Its safer to thaw in water below 40F. I always thaw large meat items in a bucket of 35-38F ice water in the fridge overnight. Smaller meats like steaks only take an hour or so to thaw.



#16 rotuts

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Posted 01 December 2013 - 09:29 AM

here is some of PedroG's work on this:

 

http://sousvide.wiki...frigerated_meat

 

If Im aware that Im going to re-heat SV from FZ the day before I leave overnight in the coldest part of my refrig. :  the lower back.

 

if not, I use hot tap water  ( 120 ) for two 10 minute cycles then into the preheated bath.

 

if just depends on what you personally think of that " 1 hour " window.



#17 Shalmanese

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Posted 01 December 2013 - 02:21 PM

Someone mentioned it being safer to thaw in the heated water bath because its quicker but i disagree. Its safer to thaw in water below 40F. I always thaw large meat items in a bucket of 35-38F ice water in the fridge overnight. Smaller meats like steaks only take an hour or so to thaw.

 

There are 3 separate procedures that need to be distinguished: thaw from frozen, reheat from frozen and cook from frozen. If your goal is to thaw from frozen for later cooking with another method, then you should ideally thaw in a circulating 4C water bath until defrosted. However, if you intend to thaw and then immediately cook or reheat SV, then it is better to combine the thaw and cook into a single step and thaw directly in the bath. 


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#18 nickrey

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Posted 01 December 2013 - 02:26 PM

Looking at Pedro's data, heating from 5C to 55C took 67 minutes. From -10C to 55C took 98 minutes but cooking to 54.9C took 75 minutes. This is most likely a function of the temperature of the water bath being set at the target temperature: it is not uncommon for extended time periods to be added if you don't cook at a slightly higher than target temperature. It looks like the rule add another third to cooking time if cooking from frozen works, at least in this instance. 


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#19 Shalmanese

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Posted 01 December 2013 - 03:18 PM

Looking at Pedro's data, heating from 5C to 55C took 67 minutes. From -10C to 55C took 98 minutes but cooking to 54.9C took 75 minutes. This is most likely a function of the temperature of the water bath being set at the target temperature: it is not uncommon for extended time periods to be added if you don't cook at a slightly higher than target temperature. It looks like the rule add another third to cooking time if cooking from frozen works, at least in this instance. 

 

Interesting, I overlaid the two graphs on top of each other: 

 

anim2.png

 

The heating curve for the frozen sample is faster initially as predicted but then slows down around the 40C mark. This doesn't seem explainable by the sample being frozen since every part is well above freezing at this point. I wonder if the frozen sample was slightly thicker than the non-frozen sample, leading to naturally longer cooking time that overwhelmed the effect of freezing.


Edited by Shalmanese, 01 December 2013 - 03:26 PM.

PS: I am a guy.

#20 PedroG

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Posted 01 December 2013 - 06:24 PM

 

Looking at Pedro's data, heating from 5C to 55C took 67 minutes. From -10C to 55C took 98 minutes but cooking to 54.9C took 75 minutes. This is most likely a function of the temperature of the water bath being set at the target temperature: it is not uncommon for extended time periods to be added if you don't cook at a slightly higher than target temperature. It looks like the rule add another third to cooking time if cooking from frozen works, at least in this instance. 

 

Interesting, I overlaid the two graphs on top of each other: 

 

attachicon.gifanim2.png

 

The heating curve for the frozen sample is faster initially as predicted but then slows down around the 40C mark. This doesn't seem explainable by the sample being frozen since every part is well above freezing at this point. I wonder if the frozen sample was slightly thicker than the non-frozen sample, leading to naturally longer cooking time that overwhelmed the effect of freezing.

 

These experiments were all conducted with the same bagged pile of wet rags with a 1mm dia temperature probe inserted through foam tape in the following order:

1. ambient to 55°C

2. 55°C to 5°C in the fridge

3. 5°C to 55°C

4. 55°C to -20°C in the freezer

5. -20°C to 55°C

I cannot rule out that the foam tape was not perfectly tight and that the bag might have soaked up some water from experiment to experiment, as I did not measure the weight of the bag before and after each experiment. This might explain the slightly slower heating rate in the experiment from frozen.


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#21 FeChef

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Posted 01 December 2013 - 08:13 PM

Guys, I have this 8/lb boneless turkey breast loaf that i cooked sous vide to 146.5F It took 4 hour to reach 130F and 8 hours to reach 146.5F. It was then flash frozen. I have decided to take the risk and bring it back to a safe temp and deep fry to crisp the skin then slice thin and portion it out into 8oz vacuum packs. If i thaw it to 38F , how long should it take to reach 135F? 2 hours? More, less? Should i set the water bath to 146.5F and give it the same amount of time as if i was shooting for 135F? Reason being is i want it to reach safe temp in as short time as possible so it doesnt spend too much time cooking and getting mushy/mealy.



#22 FeChef

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Posted 03 December 2013 - 01:18 PM

Well, the turkey breast loaf turned out great. I deep fried it for 10 minutes to get the skin really crispy. But if i ever do this again I will cook the two breast halves seperately.

 

And 24 hours later no stomach problems so thats good.


Edited by FeChef, 03 December 2013 - 01:19 PM.






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