100 hour oxtail gone bafflingly wrong

[jmbuehler]

Hi all,

 

I am rather stupmed at what happened in my circulation bath this week and would like to share and maybe get to the bottom of what exactly might have caused this.

 

Quick background: I am a German chef having learned at a 2* Michelin restaurant and now CEO of a burger chain in Germany.

 

I have a passion for biochemistry and approach virtually all cooking endeavours with an analytic mindset.

 

As I prepared a lasagna based on braised oxtail last weekend I was left with about 1300g of oxtail chunks that didn't fit into my pressure cooker.

 

Whilst braising I browsed my copy of MC searching for an interesting idea for said left over produce and stumbled across the 100 h @60C preparation.

 

I scaled the recipe to the required amount of stock and boiled it up quickly as to reduce any possible pathogens.

 

I then filled the sous vide bag with the raw, unseasoned and chilled (4C) oxtail, added the cooled stock (13C) and sealed in a chamber vaccum to -1 bar.

 

I then introduced the bag into the water bath at 60.0C, sealed the bath with cling film and checked througout the following days.

 

For the duration of the cook the bag stayed at the bottom of the bath and temperature fluctuations were at a maxiumum of 0,1C.

 

Yesterday morning (thursday, I started the cook on sunday at around lunchtime) I saw that a small bubble of bombage had formed over night.

 

Weary as to the cause, I was even more suprised to find the entire bag bloated and floating at the top of the surface when I came home last night.

 

Unsuprisingly the smell after opeing the bag was horrible and had obviously spoiled.

 

I am asbolutely flabbergasted as to what might possibly have caused this.

 

Shouldn't any possible pathogen have been killed of after at least 80h @ 60C with no sign of bacterial activity?

 

A couple of chefs I work with are equally as stumped as I and I would love, if someone on this brilliant forum could possibly offer some insight.

 

So thanks for your feedback which I would love to incorporate into the next try; after all: failure is not an option! ;-)

 

 

All the Best,

 

Johannes

[ChrisZ]

Hi,

 

I've had this happen a few times with 72hr pork belly, so I can share the input and advice I've received when I asked basically the same question.

 

The important thing is this bit:

 

"Shouldn't any possible pathogen have been killed off after at least 80h @ 60C with no sign of bacterial activity?"

 

The answer is no.  The dangerous pathogens - yes.  But not all.  The lactobacillus family, for example, is very large and many strains will survive temperatures in the mid 60s.  But they will not kill you (I guess you might get a stomach ache but overall you'd be OK).  It's a safe bet that your spoilage was caused by some strain of lactobacillus, simply because they're so common.  

 

The last time I had the same thing happen as you did, the bag smelt worse than my baby son's nappies.  But despite the smell, I did actually taste 1 small mouthful of meat and it just tasted like pork.  The smell is bad, but not necessarily dangerous.

 

​The temperature and time guidelines for sous vide are usually calculated with the dangerous pathogens in mind.  The nasty bugs that you want to avoid - e coli, salmonella, listeria and so on, ARE killed off by extended times over about 56C.  ​But the bacteria that cause food spoilage are not the same ones as those that make you sick.  It's an important distinction to understand.

 

It's probably more important to understand the reverse - that food can smell perfectly OK but still harbour dangerous pathogens.

 

The basic way to avoid these problems is to avoid contamination, which is easier said than done.  But for something like a 72hr pork belly or a 100 hour oxtail, you can always set the temperature a bit higher for the first hour (e.g. 70C for 1 hour), which may help to kill any spoilage bacteria from the bag, the stock, the surface of the meat and so on.

[jmbuehler]

Hi Chris,

 

Thanks so much for your reply!

 

And there you go, your explanation sounds very reasonable and explains what probably happened succinctly.

 

Next time I will both increase the initial temperature of the water bath and flash blanch the produce before sealing it.

 

Again, many thanks your reply.

 

All the Best,

 

Johannes

[daveb]

I described a similar problem I had with Short Ribs in this post:  http://forums.egullet.org/topic/151863-sous-vide-demo/

 

Got some great feedback.  My take-away is to dip the sealed bags in boiling water prior to dropping in a low temp, long bath.   With you oxtails all going into the same bag, only one needed to be tainted with spoilage for it to spread to the others.  Other take-away is don't cut bloated bags open

[gfweb]

Agree with the above. Esp a hotter initial cook, so that the meat temp spends less time in the range where bugs can grow.

 

Under ideal conditions bacteria can divide roughly every 20 minutes. So if food spends 40 minutes in the unsafe zone (which seems long to me) there'd only be 2 doublings of the population. Still a small number.

 

Which would be even smaller with an initial dip in boiling water.

[jmbuehler]

Hey all,

 

cheers for your feedback!

 

It is really appreciated and I will apply these lessons into all future long-cook sessions.

[paulraphael]

Hi Johannes,

 

I think Chris is correct on this. Part of the problem we face is that unlike pathogens, spoilage bacteria (and fungi) are poorly understood. We don't have ways to predict what might be lurking on the surface of the meat, able to thrive at over 50°C. 

 

Because of this, I always immerse s.v. bags into boiling water briefly before long/low cooking, to attempt to pasteurize the surface. I discuss the method briefly in this blog post. While I cannot guarantee that this will always be effective, in my experience it has worked reliably, even when doing pre-cooks at 40°C for up to four hours. I believe it is probably more effective than pre-searing (which can still be done in addition to this) because you can't reach every surface and indentation of the meat with a hot pan, especially on the sides.

[pbear]

I'd like to point out that spoilage at this temp is exceedingly rare.  Rather, most of the reports are from temps much closer to the edge of the envelope for pasteurization of pathogenic bacteria, e.g., 55ºC/131ºF.  daveb's report (thread linked above) was one of these.  By contrast, I've done a couple hundred batches at 60ºC/140ºF and have run into the problem only once.  At those odds, dunking isn't worth the effort to me.  If I run into spoilage again, and doubtless I will eventually, I'll toss the batch.  Which isn't a knock, of course, on those willing to invest in the precaution.  Also, bear in mind it'll only be meaningfully effective for things like oxtails and short ribs if they're dunked outside the bag, as otherwise the interior surfaces (where the pieces abut) won't be pasteurized at all.

 

I'm curious whether anyone knows what is standard operating procedure in commercial and restaurant kitchens.

[paulraphael]

I suspect you're most likely to see spoilage at these temperatures in cases where surface contamination was allowed to get somewhere that isn't on the surface during cooking. Like, if two ribs are butted up against one another. Or if one of the ribs got stabbed with a knife during prep. Then you get spoilage bacteria into a place that might take a long time to get up to cooking temperatures.

 

There was a thread a while ago where someone sous-vided something like a rouladen ... a piece of meat pounded flat and rolled up. The bag juices were green and smelled like baby diapers. I don't even think it was a low-temperature cook.

 

Pbear is right about the limitations of dunking. I think if you keep this in mind when you pack the ribs, you can work around it. Make sure your bag comes in contact with every surface. It might mean using a greater number of bags.  I use ziplocs, so the gaps are filled with liquid. Because of this I dunk in boiling water for a full minute. It's not important for the surface to actually reach boiling temperatures; you get 6.5D pasteurization in under 5 seconds if the surface reaches 72°C.

[dcarch]

Is it possible that the meat was bad when you bought it?

 

Vendors have all kinds of tricks to make bad meat look good and smell good.

 

dcarch

[Anna N]

Is it possible that the meat was bad when you bought it?

 

Vendors have all kinds of tricks to make bad meat look good and smell good.

 

dcarch

Hard to believe since this was just 1300 g of a much larger batch and there doesn't seem to be any indication that the larger batch was spoiled

[daveb]

I think it's almost certain that the meat had spoilage bacteria on it when purchased though not enough to detect by an off smell. 

 

Oxtail is traditionally cooked in a braise, at or just under boiling point,  which would kill the bacteria before it "blossomed".   With the low temp of SV cooking the bacteria was able to flourish while in the long bath.

[dcarch]

I think it's almost certain that the meat had spoilage bacteria on it when purchased though not enough to detect by an off smell. 

---------------------

 

Carbon monoxide is used to make meat look fresh. Bad smell can be washed away.

 

dcarch

[ChrisZ]

When it's happened me I've always suspected the stuff I put in the bag, not the meat.

 

I like to experiment with sous vide, I've always added a bit of fruit juice (or pureed pear) and wine to the bag with the pork.  After having problems I now boil the liquid for a bit first.  I have wondered if the problem I had was fermentation not spillage.

 

I like the idea of a pre-sear to add flavour as well as sterilise the surface of the meat, but the problem is judging the pre-sear so you're not actually over cooking the meat to begin with.  That kinda defeats the purpose of the long sous vide cook.  But it's pretty hard to get right, so now I just dunk the meat in boiling water for a few seconds.

 

Since I started the practise of boiling any cooking liquids first, and dunking the meat in boiling water for a few seconds too, I haven't had any more problems.

[pbear]

Hard to believe since this was just 1300 g of a much larger batch and there doesn't seem to be any indication that the larger batch was spoiled

 

Recall that Johannes cooked the rest of the meat (the main part, actually) in a pressure cooker.  It never had a chance to spoil.

 

When it's happened me I've always suspected the stuff I put in the bag, not the meat..

 

Conversely, I almost never add anything to my pouches except salt.  This may be why I've had only one failure (so far).

Edited September 20, 2015 by pbear (log)

[KennethT]

When I do long low temp cooks, I'll presear with the propane torch, rather than in a pan.  I find it much easier to get into all the crevices with the torch, and I've never had a problem.  Then again, I could have just gotten lucky and not had the spoilage bacteria present in the first place... we'll never know!

[paulraphael]

It should be fairly easy to pre-sear without overcooking. If you have trouble getting a pan or griddle really hot, you can get some chemical help. I make a 1:5 mixture of baking soda and dextrose, and sprinkle it very lightly on the searing surfaces. You get very rapid browning, even on a medium-hot pan.

 

The bigger trick, I find, is getting to all the surfaces, especially the sides and any uneven parts of the meat. This is why I like to dip.

 

I find torches a bit tedious for this kind of thing, but someday might get a Searzall. That gizmo looks promising, at least for smaller quantities.

 

A deep-fryer would make short work of all of this.

[KennethT]

Yes, a deep fryer would be fantastic!  The torch I have is a searzall hose torch which produces a large 'swirl' flame.  It makes a big flame, and I've never had an issue with torch taste.  Plus, an added bonus is that the tank hangs from your belt and you can then use the torch at any angle, whether the canister is full or almost empty.

[gfweb]

I dont think presearing for bacteria killing purposes wouldn't benefit from adding bicarb which only enhances the Maillard rxn.

[paulraphael]

I dont think presearing for bacteria killing purposes wouldn't benefit from adding bicarb which only enhances the Maillard rxn.

 

That was in response to someone saying they had a hard time pre-searing without overcooking.

[TdeV]

Earlier this thread, several folks mentioned dipping the bag into boiling water. Do you mean turn the bag inside out and then dip it? Don't you then have to wait for the bag to dry in order for the vacuum to seal properly?
 

Are people saying it would be satisfactory to dip the oxtail in boiling water for 5 seconds?

[Smithy]

No, they mean to dip the vacuum-sealed bag in boiling water to sterilize the enclosed surfaces.

[EnriqueB]

I have also had many reports of people experiencing the same problem when cooking for long times between 55 and 60ºC, though I have never seen it myself.

 

I agree with the explanation by ChrisZ, I believe this is due to spoilage and not pathogenic bacteria. Althouh I also have some serious concerns about pathogenic vegetative bacteria disactivation around the no-growth/growh threshold (generally assumed to be 54,4ºC for Listeria, the most heat-resistant vegetative pathogen). For both reasons, I always recommend to pre-sear (reaching all surfaces, so a torch is my favorite) the meat or scald the bag in boiling water for these profiles (<60ºC for more than 6 hours).

Edited September 24, 2015 by EnriqueB (log)