i've pulled some meat out of the freezer that was burnt pretty bad. all grey and dry.I'm not sure how the process of freeze drying actually works, but I'm confident there's more to it than chucking something in a freezer. The moisture's got to go somewhere and there's not a lot of air volume in a typical home freezer to take it away and keep it away from the item you're freeze-drying.
you have to leave it open to the air. just hang it from a rack in the freezer.