Dry ice genuinely works and costs $10 to $30 per batch. A household freezer does not - that produces freezer burn, not freeze-dried food.

12 to 30 hours for most loads. Manufacturers publish 12 to 20 and 16 to 30, both against partial loads. Here is what actually changes the number.

Freeze drying removes 98 to 99% of moisture and keeps the structure. Dehydrating removes 80 to 95% and collapses it. Both have cases where they win.