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 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.)