A good measure for cutting materials is finger thickness, not more than that. Anything more than 15 mm thick will dramatically prolong the freezedry cycle, you may do it but expect longer cycle times even up to a few days. Remember cycle time is always defined by the thickest slice! Thinner the slice, shorter the cycle! Always evenly spread across all trays.
Newer mix different products!
Materials may be frozen directly on freeze dryer trays in a conventional or a blast freezer!
If frozen in bulk make sure it does not stick and freeze together, always slice or piece by piece. The product is correctly frozen when all water is crystallised, not only the surface layer.
Non-frozen products will be deformed and dried by evaporation that will cause major product reshaping. Might also be dangerous for the equipment if the product is bubbling. A good rule of thumb is to freeze overnight!
Once the material is frozen, transfer the product from the freezer to the freeze-dryer chamber as fast as possible.
None of the material should get melted! It is of critical importance to start vacuuming in a matter of seconds!