Note added November 1, 2017: I have finally solved this problem! Check out my solution to prevent a bad smell when cooking sous-vide for a long time at a low temperature.
The internet is such a great place. Not only have I met my husband online (in the previous century, when that was not common yet), but it is also a great source of inspiration and help. When I wrote about the bad smell that I got just once when I cooked wagyu beef sous-vide, one of my readers, a guy called Guido, pointed me to a post on SeriousEats where a representative of SousVide Surpreme wrote: “An odd smell occasionally occurs in long cooking of meat (beef, pork, probably lamb) because the low temp doesn’t kill off lactobacillus type bacteria (the ones used in making cheese, buttermilk, yogurt). This bacteria is not harmful, it just may give the meat a ‘stinky cheese’ odor. The meat can be seared and eaten and it won’t affect the quality or flavor of the meat. It can be minimized by searing all sides of the meat (the bacteria are on the surface) with a kitchen torch or on the stove top before vacuum sealing and cooking.”
I think that it is quite likely that some lactobacillus type bacteria was the culprit making my wagyu beef stink. It also made me realize that the funky smell that tough cuts of lamb (shoulder or neck) often gets when I cook it for a long time may not be attributed to the lamb being male after all.
Since the bacteria are on the surface and the SVS guys advised that it can be minimized (but apparently not completely eliminated) by searing all sides of the meat before vacuum sealing and cooking, I thought it might be even better to scald the meat in boiling water before vacuum sealing and cooking to eliminate the bacteria completely.
To test my theory, I bought a piece of lamb shoulder and experimented with it.
I started by cutting the lamb into three pieces.
I seared one of the pieces on all sides in very hot clarified butter.
Another piece I scalded in boiling water.
After 10 seconds or so, the outside is completely sterilized.
I vacuum sealed all three pieces separately. From left to right: raw, scalded, seared.
I cooked all pieces sous-vide for 24 hours at 57C/135F. From left to right: raw, seared, scalded.
I opened them from left to right and was very surprised that the raw one did not have a funky smell. It just smelled of lamb. Although lamb cooked without heating it before sealing has often had at least a bit of a bad smell when I cooked it, this time around there was nothing wrong with it.
Then I opened the seared piece. It was no surprise that one was fine as well.
But then surely the scalded one should be fine as well? As you may have guessed by now, it wasn’t! I’ve actually never had a piece of lamb smell so badly. It was so bad that we didn’t eat it (even though it would have been safe to eat).
This poses many questions:
- Is indeed lactobacillus the cause of the bad smell of the final piece?
- If it is, was the lactobacillus on that piece already and did I not sterilize it carefully enough? (I did use the same tongs to lower it into the boiling water and lift it out of there again, but that should also sterilize the tongs, right?)
- Or did the piece get infected with lactobacillus from another source such as my hands? If so, why didn’t I infect the other two pieces as well?
- How is it possible that the lactobacillus was only on one of the three pieces that came from the same piece of lamb shoulder?
I’ve decided I need more data points to build a theory, so I’m going to repeat this experiment. I will let you know what happens.
If anyone has any wisdom to add, please don’t hesitate to leave a comment. (By the way, even though the pieces are in a different order in the photos, I am positive that I did not mix them up. It was easy to see the difference between them, also after cooking them sous-vide.)
We did eat the other two pieces of lamb shoulder and they were absolutely wonderful after a quick sear in very hot clarified butter.
Stefan's Gourmet Blog 
Mmmmm interesting test. I have no sage wisdom on the matter but it would be good to clarify the cause of the small and come up with a definitive resolution.
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that is bizarre! i wonder if there is a different reason why the scolded piece got smelly. Lactobacillus should have been more or less equally present in all 3 cases. This is definitely a disorienting result, but really interesting. I can’t wait for you to post your next test. I know exactly what smell you’re talking about. And I too have thrown meat out because of it being too intense, specially in cases of 48+ cooking. thanks Stefan!
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Solved it! See my latest post.
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I love how geeky this post is, even if it’s not scientifically sound, it’s interesting to ponder anyway. Glad 2 out of 3 were delicious. I’d be sad if the stats were the the other way around!
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I find your test results fascinating, Stefan. I’ve no experience to draw upon but cannot wait to see what other sous-vides users have to say, not to mention your future test results.
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I just rescued this comment from my spam queue?! Very strange that it ended up there — you are one of the least likely people to spam I can think of 🙂
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This is such an interesting preparation. You a food scientist and chef! I love lamb – and it looks so tender and succulent.
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Thanks Shanna. Lamb shoulder or neck sous-vide is great, especially when served with goat cheese. https://stefangourmet.com/2012/07/13/lamb-shoulder-sous-vide-with-goat-cheese/
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Oh my. Did someone say chèvre? I love the combination fo the two! Reading this post ASAP! Thank you so much, Stefan. You are quite the chef and gourmand.
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Hey Stefan, thanks for conducting these experiments – it’s great for amateurs like myself to have such resources. Looking forward to further results.
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Interesting Stefan. Baby Lady doesn’t like lamb so I don’t fix it often although Cabrito may be on the menu when you arrive. I will be interested in your further data.
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That’d be nice, as I don’t think I’ve ever had goat other than in Indonesian kebabs. I hope I can shed some light on this with further experiments, because it’s gotten to the point that I don’t want to risk cooking lamb sous-vide for company as I never know when the bad smell will hit.
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Stefan, I’ve tried 72-hr short ribs twice and had horrible smell problems both times. The first time I started raw. The second time I seared with a blowtorch before bagging. There was virtually no difference in the result so I can’t see how lactobacillus can be the culprit. Even if the torching didn’t kill it all, it should have significantly minimized the population to make a difference, it seems to me. It amazes me that this issue is still a mystery after so many have reported it.
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Craig, thanks for visiting and taking the time to leave a message. It certainly amazes me as well. I guess more experiments are needed to figure this one out.
The explanation I could offer for your experiment is that you could have contaminated the seared meat with lactobacillus again after searing it but before vacuum sealing it. A significantly minimized population could easily regrow as the bacteria can still grow at the cooking temperature. I will definitely post about it on my blog when I figure this one out.
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Solved it! See my latest post.
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I’ve had a similar experience doing 48H pork shoulder. I’ve had the smell happen when putting it in raw. I read online about searing/boiling it. I’ve only tried searing once and that seemed to help (but I need to test again). I tried boiling and it definitely does not help. I just made some today and the smell is worse than ever! (maybe exaggerated because I’m just disappointed).
Any further discoveries about the cause?
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Solved it! See my latest post.
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