Six years ago I did some testing and concluded that there was no added benefit of cooking scallops sous-vide before pan searing them.
However, scallops were on sale by the kilo (2.2 lbs) jar at the market, and because of that buying the whole jar was less expensive than the amount that I actually needed. I had about 450 grams (1 lb) of scallops left over, and with the expiry date quickly approaching I needed to think of a solution. Freezing is not a good idea, as that would damage the texture of the scallops, and scallops in jars already have been frozen and defrosted, so it is advised against to freeze them again.
(By the way, scallops are much better when you buy them in the shell and shuck them by yourself. However, they are hard to find and expensive like that. In a jar as shown they are easier to find, but treated with preservatives and soaked in a brine. This makes them harder to sear, as they will release the brine when they are cooked. More about different qualities of scallops here.)
I decided to vacuum seal the scallops, and cook them sous vide to pasteurize them. Pasteurizing means heating the food to a certain temperature for a time that is long enough to kill most ‘bugs’ at that temperature. You can read more about that here.
I cooked them sous-vide at 55C/131F for 2 hours and 30 minutes. Given the thickness of less than 2 cm (3/4 inch) after vacuum sealing (which flattens them a bit), that is enough to pasteurize them. I was bit worried that the higher temperature (as I cook most seafood usually at 50C/122F or less) and long time would be bad for the texture, so I treated this as an experiment.
As you can see they released quite a bit of liquid, about a third of their total weight. They would have released at least the same amount of liquid if I had tried to sear them before cooking them sous-vide.
Now that they were pasteurized, I could store the vacuum sealed scallops in my refrigerator for at least a week. This is because my refrigerator is set to 3C/37F. At 5C/41F it would be only 3 days, and at 1C/34F even 30 days! (So this is a reminder that the temperature setting of your refrigerator is very important when it comes to the time you can store food in it without spoilage!)
When I took the scallops out of the refrigerator, I opened the bag and discarded the liquid. Then I patted the scallops dry with paper towels..
…and seared them over high heat using vegetable oil. Please note that as the scallops come out of the refrigerator, you can sear them as if they were still raw.
I was very happy with the result, as (1) it was easier to get a good sear on the scallops because they released a lot less liquid than the raw ones would have done, and (2) the texture was fine. I did not do a side by side test, but I would say that the texture was very similar to what it would have been if I had seared them directly from raw.
So my conclusion is that there is a use to cooking scallops sous vide after all, namely to pasteurize them for longer storage.