Reheating with Sous Vide--Methods and Food Safety

[fzxdoc]

I'm wondering about using sous vide to reheat foods. I can't convince myself that it is a safe method, although it should be since so many people do it and the Chef Steps (Joule) site recommends it.

The rule of thumb that I often see all over the internet is to set the water temp a few degrees below the temperature at which the food should be cooked, and reheat the food for 45 minutes per inch thickness of the food in the SV bag. This recommendation is for food cooked in any manner, not just sous vided in a sealed bag, flash chilled, stored and reheated.

The Chef Steps site is a bit more precise. It has tables for recommended times when reheating both refrigerated and frozen foods. But they stress repeatedly that these times are not pasturization times. I'm guessing that these are just times that it would take to get the center of the reheated food up to the same temp as the water bath, but I could be wrong about that.

So, aside from the obvious benefits of reheating to the perfect food temperature and not overcooking leftovers, does anyone have information about the safety of reheating in this manner?

FWIW, the FDA says leftovers should be reheated to 165°. That's a great way to ruin a reheated piece of steak, I'm thinking.

So I'm looking for info/input to convince me that reheating using sous vide is a great (and safe) thing to do.

Kathryn

[HouseHomey]

Provided the food was handled properly you want to heat your food to above the minimum holding temp of 140°.

40° to 140° is considered the danger zone so when reheating food you want to use the same standards. Pasturization is a specific time and temp relationship.

Also if you reheat in a zip loc rather than vac seal you can open it and probe it with your Thermapen.

[shify]

But the danger zone is for holding food. Assuming you are reheating, i.e., getting it up to a palatable eating temp, I wouldn't worry as much about the danger zone. Warm it up enough to to your taste and then immediately serve.
That being said, the chef steps time seem odd to me. From fridge temps, I can't imagine a 1 inch steak to take an hour and a quarter to get up to serving temp.

[fzxdoc]

I'm with you on questioning some Chef Steps recommendations, shify . Even though they have the luminary on sous vide safety on their payroll (Douglas Baldwin), I wonder how often they pay attention to him.

HouseHomey thanks for the clarification of your thoughts in your subsequent post. You're a careful and excellent cook, and I appreciate your comments.

Kathryn

[Skip]

Great post fzxdoc . I've wondered about reheating food too! Anxious to read some replies to your post.

[shify]

I've reheated plenty of meats in sous vide and only leave it in there long enough to reheat it to your desired temp. For shorter duration cooks, I don't bother sealing the bags and just use ziplocs and clip them to the pot so it is easy to temp probe the steak or feel the pulled pork to see if its warm enough for my taste. if not, just re-clip it and check again a few minutes later.

[choffert]

I use the sous vide for reheating all the time. We pre-portion pulled pork in vacuum bags (who can eat a whole shoulder?) and pop it in the bath for an hour or so from frozen @140-145 and it's perfect.

[rodkeary]

I've just started reheating from frozen as well. Only done pulled pork but did it @ 160 for an hour. Worked very well.

[OSB]

This sounds like the way to go. Straight from the freezer to the hot tub. I will give this a shot for sure.

[Troutman]

Maybe I'm missing something here but we're talking about cooked meat, not raw. It's either held in the fridg for a couple of days or it's frozen for another time, after cooking. Regardless it's never at an unsafe temperature. Re-heating, however you do it, for immediate consumption should be just fine, as others have said we do it all the time. Does it have to go 140* to be safe? I say no, if I cook a steak to medium rare, call it 130*, then hold it a 35* or below (or even freeze it), then bring it back up to about the same temp as I cooked it at, where is the problem occurring?

[Potkettleblack]

So, let's look at some situations.
1- I have cooked a thing sous vide to a Baldwin certified pasteurization time@temp curve, or beyond. Let's call this Short Rib
2- I have cooked a thing sous vide to a minimum to get it's temp up, but do not hold it at the Baldwin pasteurization time/temp curve. We'll call this Steak.
3- I have cooked a thing on the grill/smoker, to completion, then vac sealed it whole. We can call this Kalua.
4- I have cooked a thing on the grill/smoker, to completion, served part, then vac sealed the leftovers. I don't really do this, so I don't have an example.

So, case 1, short rib. As long as I have not cracked the seal on my short rib's bag, and I drew a good seal on it, I have not undone the pasteurization. I have shocked it cold before storing (because that's safety in a lot of directions). My concern, as long as I haven't broken the seal is autolysis, not a bacteria issue. With the sous vide cook, I have never really taken it out of the zone, but I take it back down, rapidly, and then warm it slowly with sous vide. I've never really autolyzed anything, even with 75 hour short ribs.

Case 2, steak. When I do this, I generally shock and then sear, straight away. If I'm storing, I take it to a pasteurization time.

Case 3, I've put my Kalua into the vac, while it's fully cooked, and still intact. It is safe at that moment. I've vacsealed it, shocked cold, and stored. Then I've brought it up gradually. This is not terribly different from using a cambro to hold it, only I'm bringing it up, rather than down, I'm going faster up than the cambro goes down, and I took it through the zone going down as quickly as possible. If I were really concerned (like a really big hunk o meat, like a brisket), I might've added 10% salt to my ice bath to lower the temp of the ice water, so as to get a faster shock.

Case 4, As I said, I don't really do that.

Truth be told, I tend to do most of my reheating without the sous vide. Either on the Grilla, the Weber, or the Science Oven. I'll be completely honest... I had leftover ribs for breakfast that I reheated in the science oven at work. I don't think I made them any worse... An oven would have worked better, but we do the best we can.

If this is TL, allow me to summarize:
Shock before the fridge. Always. It produces better results and it is super food safe.
If you're going to store, pasteurize.
If you pull pork, vac seal and reheat gradually, you're on your own. I'm not saying it's not safe, I'm just saying it's not how I roll (I like to reheat pulled pork on a sheet pan under the broiler, with some extra sauce on... that's the most amazing use of PP.

[fzxdoc]

The thing about cambroing is that the food never gets to the danger zone. It's always kept well above 140°. It's the moving of the food through the danger zone as quickly as possible that seems to be the key to food safety for storing as well as for reheating. That's the take home message I'm getting from you, Potkettleblack. Thank you for your thoughts, including those in your subsequent post.
K.

[Potkettleblack]

Ah, that wasn't enough.

Norm is my spirit animal:

http://sousvideresources.com/2016/07/21/shock-treatment-is-safe/

A NOTE ON RETHERMING.

If you treat your food lovingly on the way up, and then on the way down again, you want to make sure you use safe practice when you decide to retherm. I have observed people advocating retherming via sous vide at a lower temperature than the original target, and this is really not a good idea. The same safety guidelines exist regardless of whether or not the food has been pasteurized previously, if only to avoid autolysis. Sous vide is not necessarily the best application for retherming, because time spent in the danger zone is cumulative. Most traditional methods spend LESS time in that danger zone than sous vide does.

So, for me, once I’ve taken that chicken or pork or whatever up the ladder and then gently lowered it down again, I leave it sealed in the bag until the day of service. I crack the bag, and saute, roast, bbq, grill, baste, deep fry, boil, whatever (did I forget any?) just like it was never processed in the first place. Just like Sous Vide never existed.

Some people want to argue that, if you’re going to do that, why would you sous vide in the first place. I have engaged in these debates, but, ultimately, I rely on that old truism: THE PROOF IS IN THE PUDDING

And maybe this is more your speed and answers all your questions:

http://www.hi-tm.com/Documents/Chillfd.html

[choffert]

I don't think sous vide reheat is any slower. Sure the microwave is faster, but who wants the result. By staring at the temp I need when putting the food in (vs. allowing the water and food to come up to temp together), I see a much more efficient transfer of heat into the food vs. an oven or even a grill. Water conducts heat much better than air...

[choffert]

The other consideration is how long do I hold the food at the reheat temp...I leverage the ability of the sous vide to maintain temp for a long time...toss a bag in the bath on the way to work and by the time I get home it has been at temp long enough to kill off any bugs which might have been packaged.

[Potkettleblack]

As I said, I don't really have a comment on the process of shredding, sealing, and reheating. I don't do that, as I don't have a use. If I make PP, I tend to eat it all week or for a crowd. With the Kalua, it was gone in a day, so no issues. The science oven is a very fast reheat method, and, with a bit of practice, produces great results.

[Troutman]

Kind of hard to grill Kahlua ?? Even so it makes for a great White Russian or even a B-52 shot !!!

[jfmorris]

Potkettleblack I think I am with your last source here on this. I feel that using sous vide to slowly reheat, if the food was ever unsealed and had potential of microbial contamination - true of all food that you've seared and touched with anything that was not sterile - is not a good idea. Too much time in the danger zone compared to other reheating methods. And I get your concerns with shredded pulled pork. The act of pulling pork mixes up post-cook contamination into the meat. You need to now pasteurize it again. Maybe an hour at 140 is plenty to do that. It probably is.

I've never used my Anova to reheat as I am not that patient when reheating leftovers.

[CaptainMike]

Thanks for bringing this up Kathryn, it is something I have been contemplating lately. My intuition tells me that SV might not be the safest way to reheat leftovers and PKB's analysis and shared data indicates as much. Saved me a bunch of computer time!!

[fzxdoc]

I agree with you, CaptainMike. Seems like reheating should be done by a fast heating method, not one that takes the food through the danger zone more slowly like sous vide.

K.

[Spinaker]

I do it all the time, at least a few times a month. I use Sous Vide to reheat brisket, pork shoulders, pastrami, you name it. I have never had any problems. As long as you shock the meat in a large container full of ice water, and get the temp down quick, then you are just fine. Obviously, you need to be careful how you handle any food, but I have never had any problems and the food always comes out great.

[Spinaker]

I reheat in the bags, so the pasteurization is not broken. Shocking quickly in a large container, is key. In the winter the bucket is outside in the sub-zero temps to help the meat temp get down. Needless to say, get that temp down quick. And I always reheat the water to 165 F and throw the bags in for a couple of hours to make sure everything is heated. Larger cuts get more time. CaptainMike

[CaptainMike]

What about things like casseroles and enchiladas?

[Spinaker]

No idea, that is a new one on me. I have only done it with cuts of meat. CaptainMike PKB might be the guy to answer that one.

[JGo37]

What I've found out here is that I'm setting my freezer to 0-F.

I've always filled my table-top roaster with water, preheated to the temp I want, and reheated. It's pretty accurate across the range. This discussion tells me I've avoided stomach bugs by luck.


Maybe an InstaPot has a play here - faster?

[fzxdoc]

I'm getting the vibe from Potkettleblack 's post that the fastest method of reheating is the safest thing to do. Instant Pot takes about 20 min or more to come up to pressure and then heats to super hot temps above boiling which might overcook your already-cooked food. Seems like there might be quicker methods than the IP. More research needed!

[JGo37]

I've got an IP clone that has warm and steam options, and I don't have to secure the lid to heat it up, but I can't control the actual temp. I was thinking that dropping something into steam may be quicker than sous vide, but I don't really remember if the coefficient of heat transfer drops dramatically for water in gaseous state.

[HouseHomey]

Potkettleblack thank you for that thoughtful response. I clocking in at 5:45 this morning I was in a hurry for time and didn't have time to compose a thoughtful response and I apologize for that.
Troutman Spinakershify

first of all please notice that I said " provided that the food was handled properly." That sentence says a lot because I was in a hurry for time I'm not sure that came across correctly. That's assuming that you handled your proteins correctly help them and brought them down in the appropriate times to the appropriate temperatures and then stored them correctly in the appropriate manner.

did you bring the food up to sufficient temperature for whatever it was you were making? Did you cool it down to less than 90° within two hours appropriately for the food you were making? Did you get it to below 40° and into the frozen state below the next two hours? Did you hold it and ice chest or a blast chiller?

and I can't tell you how crazy it makes me to hear "well I've never had a problem before." You know my friends parents have been doing heroin for 15 years and they're still not addicting." Just because you haven't had an issue doesn't necessarily mean that it's not dangerous behavior. If the bacteria is present or whatever it is you were concerned about and you don't handle your food properly that is still going to be present when you go to reheat your food. This is why you get it "Out of the danger zone's for the appropriate amount of time."

PKB thank you for so much for saying that if you pulled your pork and then re-vacuum sealed at that all bets are off because that is exactly right and most people don't consider that. So when I said "provided your food was handled properly" there was a lot of fact in that sentence.

honestly I'm not sure I'm any less guilty than the rest of us. But please just don't think you could reheat your food and think you're OK because you have not had a problem. That is simply not the case.

Jerod Broussard where do you stand on this?

PKB PROPS BROTHER.

[fzxdoc]

I'm not sure it's an issue of being less guilty with respect to reheating methods, HouseHomey , more like a learning curve. Most of us have never had a sous vide option before and are trying to figure out what its safe uses are. Supposed experts like the Chef Steps folks say sous vide reheating is a good idea but don't address the safety concerns. So we're all questioning here...

[fzxdoc]

...And thanks for your clarification of your earlier post. I knew what you meant.

K.

[Jerod Broussard]

Sous vide does such a great job of transferring "wet heat" the risk is very minimal.

Obviously if things are mishandled and toxins are in play things change big time. Generally you are looking at the improper cooling down of LARGE quantities of gumbo, soup, and pastas as the main culprits of food poisoning outbreaks. Not single cuts of meat that are sometimes smoked to 200+ internal.

[surfdog]

I think this is where most people get it wrong. They don't take cooling into consideration. They cook it, get it to an "acceptable" temperature, and later just let it cool down. O_o Other than at other chef's homes, I've never seen a cooling paddle in anyone's kitchen for instance. THAT seems more problematic than the few extra minutes the SV might take.

[EdF]

I think JGo37 and Jerod Broussard and surfdog (and all the other contributors) have got it right: proper handling.

[Potkettleblack]

Well... sure.. but the reason I have more concern about pulled pork versus unpulled pork is a matter of surface area. More surface area, more bacteria. More surface area, more chance for cross contamination. But, I don't do a lot of pulled pork, and I reheat it under the broiler, because I like the crispy edges you get doing that. But sure, the start is important.