2

There seems to be a lot of debate regarding the advantages of pre-searing meat prior to adding it to the water bath. I understand that the post-sear process is mainly for appearance and taste purposes, but some chefs I have watched have suggested that post (and pre) searing is essential for killing off any surface pathogens.

While this is fairly easy to accomplish with a thick cut of steak, with thinner cuts (and chicken breasts, for example) it is difficult to accomplish.

While I have no intention of cooking below recommended pasteurization temperature/timings, for the acutely food safety conscious, would a 60 second blanch in boiling water prior to immersion be a sensible step? My reasoning here is there will still potentially be areas that do not reach sear temperature. Or is this only a useful technique if you intend to serve unpasteurized dishes?

  • debate ? do you have references ? – Max Jun 6 '18 at 17:27
  • Chefsteps say pre-sear, Serious eats say it makes little difference. Various YouTube chef's vary, but one seared his chicken after 2 hours at 66C and stressed the importance to kill off residual toxins. – Greybeard Jun 6 '18 at 23:23
  • 1
    What are "residual toxins?" – moscafj Jun 7 '18 at 0:41
  • I'm assuming here, but what I think what the chef was getting at was any bacteria etc. that was present on the surface of the chicken. That said, I think most people would agree that 66C would be enough to destroy any accumulation of anything nasty on the surface over a 2 hour period. I don't think they fully grasped the principle of time+temperature=safe to eat, hence my question. – Greybeard Jun 8 '18 at 1:37
3

Pre-searing and post-searing are generally employed for crust formation on the final product. In fact, when cooking something like a steak, a pre-sear, followed by sous vide, finished with a post-sear allows quicker final crust formation. This reduces the possibility of over cooking your steak with the final sear. This works with poultry as well.

A quick blanch can be helpful when cooking meats at a low temperature, for a long time. This blanch eliminates lactobacillus, which is not harmful, but could cause off odors and bag inflation. For example when using a low temperature water bath (sous vide) to cook short ribs for, say, 48 hours...or something like oxtail, which I have done for as long as 100 hours, a quick blanch at the beginning drastically reduces any surface bacteria that might incubate and inflate the bag. Searing will serve the same purpose, but sometimes, with irregular cuts, it is difficult to sear all sides. Generally, I would suggest a very good sear, or a blanch when using low temperature, very-long duration (12 + hours) cooking situations.

Also, a quick blanch before cooking some vegetables will deactivate browning enzymes, and could be useful.

  • The surface bacteria will be killed almost immediately during sous vide cooking because they're on the surface. Do you have any evidence for your claim that blanching is actually better? I never blanch my meat, and I've never had any bag inflation. Maybe that's because, like the OP, I cook my meat at pasteurization temperatures. – mrog Jun 6 '18 at 15:59
  • 1
    @mrog one has to keep in mind that eliminating pathogens is a function of time and temperature. One of the advantages of sous vide is that you can use lower temps for longer times, thus eliminating pathogens. In some circumstances, surface bacteria will not immediately be "killed". There is potential for growth, off-gassing, and bag inflation prior to the product reaching a safe temperature. – moscafj Jun 6 '18 at 16:35
  • The OP stated, "I have no intention of cooking below recommended pasteurization temperature/timings." Surface bacteria die in just a few minutes at pasteurization temperatures, long before the inside of the meat is pasteurized. – mrog Jun 6 '18 at 17:11
  • I've never had bag inflation, but I've never cooked longer than 36 hours and I always keep the temperature at least 55C. If you've had bag inflation, maybe your temperature was too low for pasteurization, or maybe your meat was contaminated with non-pathogenic organisms that could withstand the heat. Either way, it's outside the scope of the original question, which is about food safety issues at pasteurization temperatures. – mrog Jun 6 '18 at 17:21
  • 1
    @ChrisH depends (a) if lactobacillus is present, and (b) how much is present, and (c) how long the surface temperature remains in the 30 - 45C range, which is the optimal growth temperature. Main point: it is not always necessary to blanch. When it is a good idea, a quick blanch is most efficient. – moscafj Jun 6 '18 at 19:37

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.