Eggs and milk work well. Cheese depends on the fat content, and butter does not work at all. Fat is the variable that decides almost everything here.
Why fat decides what works
Freeze drying removes water. It does nothing to fat, and fat goes rancid through oxidation whether the food is dry or not. So the higher the fat, the shorter the storage life, no matter how well you seal it.
That single fact explains the pattern: skimmed milk keeps longer than whole, hard low moisture cheese keeps longer than soft, and butter is not worth attempting.
Eggs
Whisk raw eggs, pour a thin layer onto lined trays, freeze dry, then powder them. They rehydrate into something that scrambles and bakes well, though the texture of a plain scramble is noticeably softer than fresh.
The safety point matters: freeze drying does not pasteurise. Raw egg powder carries whatever was in the egg, so it must be cooked thoroughly after rehydrating. If you want an egg powder you can use uncooked, cook the eggs before drying them.
Milk and cream
Milk freeze dries well and rehydrates close to the original at a ratio of roughly one part powder to seven or eight parts water, though it takes a minute of stirring and tastes slightly flatter.
Cream can be dried but has a much shorter storage life for the fat reason above. Treat dried cream as a months item, not a years one.
Cheese, by type
| Cheese | Result |
|---|---|
| Grated hard cheese, cheddar, parmesan | Good. Crisp, keeps well, melts back into cooking |
| Mozzarella, low moisture | Good, best shredded |
| Cottage cheese | Works, useful in cooking |
| Brie, camembert | Poor. Too much fat, dries greasy |
| Cream cheese | Mixed. Thin layers only |
| Butter | No. Fat with barely any water to remove |
Storage and rehydration
Powder and grate before drying where you can, since surface area does the work. Seal into mylar with an oxygen absorber immediately, because dairy powders pull moisture out of the room within minutes.
Rehydrate with cool water for milk and eggs, then use as normal. For cheese, most people skip rehydration entirely and drop it into a sauce or a bake dry.
Questions people ask
Are home dried eggs safe? Only when cooked after rehydrating, unless you cooked them before drying. Freeze drying does not kill pathogens.
Which cheeses work? Hard, low moisture, grated ones.
How long does dried dairy keep? Skimmed milk powder years when sealed with an absorber; anything high in fat, months.
Safety note. Freeze drying does not pasteurise and does not kill Salmonella. Treat raw egg powder as raw egg: cook it after rehydrating, and keep raw egg away from other food and surfaces during preparation.
What this is based on
- USDA and FSIS guidance on eggs and egg products
- Manufacturer guidance on freeze drying dairy in home units
- University extension publications on home food preservation of dairy