I've had good results putting sealed vacuum bags in boiling water but as mentioned 40# could be a challenge. I did an interesting experiment last week that worked out really good and would work for that much sclced. I put sliced left over brisket in a service pan with a rack in the bottom (to elevate the brisket about 1/2" off the bottom of the pan) then I made some beef au jus using the concentrated paste stuff in a jar, and added to the pan under the brisket. Sealed tightly with foil and reheated in a 250* oven for an hour. The brisket was very good and not dried out plus the au jus was a tasty bonus.
I know it is too late, but best thing is to not slice it until ready to serve. Reheating it whole will retain the moisture a lot better. ^^^^:thumb:
I made some beef au jus using the concentrated paste stuff in a jar, and added to the pan under the brisket. Sealed tightly with foil and reheated in a 250* oven for an hour.
I haven't had to do 40 pounds worth before. But when I made a 16 pounder for the Super Bowl party at the local bar, I cooked it, sliced it, and threw it into my big crock pot with the remaining juices and a little beef broth. I knew I didn't want to be standing there slicing as we went. Put the crock pot on warm and we ate it many hours later. I got lots of compliments on how tender, juicy, and flavorful it was.