Four Basic Steps
Every batch that goes through a freeze dryer follows the same basic sequence, whether it's a home operation or a commercial one: Clean and cut (or pour) — wash and prepare the produce, cut it to a size that dries evenly, or for liquids (soups, sauces, purées) pour a thin, even layer onto the tray. Pre-freeze — get the product solid before it goes into the machine. Many operators pre-freeze in a standalone freezer first, which shortens the freeze dryer's own freezing cycle. Freeze dry — the machine runs its freeze cycle, then pulls a vacuum and slowly sublimates the ice directly into vapor, without the product ever thawing. Package immediately — freeze-dried food is highly hygroscopic, meaning it pulls moisture out of the air fast. Seal it right away, airtight, usually with an oxygen absorber, to protect that 20-to-25-year shelf life. Simple on paper — but each of these four steps has its own details and pitfalls worth knowing before you start. Future posts in this section will dig into each one.