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?
Best Answer
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.