I feel the need to address this topic since it is related to sous vide. So, I sous vide alot of chuck roasts for italian beef sandwiches. I freeze them in 2 ounce portions. I make really concentrated beef stock from roasted neck bones (there cheap and gelatinous) and i flash chill in ice water and freeze. When i am ready to make an italian beef sandwich i boil the stock, let it cool down to around 140F and dip the frozen pre sliced beef into the juice in my sous vide vessel. It may sit for a few hours and while this is sitting, that stock is building flavor. After i serve the sandwiches i flash chill and refreeze. Each time i repeat the process, that stock gets better and better and nobody ever gets sick.
I also "Top" this stock with "new" stock when it starts to get low from the sliced beef absorbing the juices.