I've got a food saver model V845 that I use for vacuum packing fish. I've always tried to lightly 'pre-freeze' my fish before vacuuming to prevent excess liquids from getting into the machine and ruining it. I typically prefreeze for about 1hr to where the fish piece is still flexible and not really frozen, but the juices are mostly frozen. But when I do this, the food saver doesn't seem to pull enough vacuum to really get the air out of the package. I'd say it is 90-95% vacuumed, but I can actually pull on the bag and get it to wrinkle and get a bubble over the fish. It seems that because the fish is still somewhat soft, it can't pull enough vacuum to get all the air out.
The only way I can get it to get all the air out is to completly freeze the fillets before vacuuming. If I freeze the fish overnight on cookie sheets and then vacuum, it works well because the fillet is more solid and it pulls all the air out around the fillet.
So my question is, does it hurt anything to completely freeze the fish before vacuuming? I am wondering if it will freezer burn faster by doing this?