HOW TO FREEZE DRY FOOD
1. Choose the types of food you want to freeze dry. Foods that contain high amounts of water work best for freeze drying. Their structure remains intact after the process. These foods hold up particularly well:
- Fruits like apples, bananas, berries, persimmons and pears.
- Vegetables like potatoes, peppers, carrots, sweet potatoes and parsnips.
2. Choose the freshest food possible. Freeze drying food at the peak of its ripeness or freshness helps make sure it will taste good when it’s reconstituted. Fruits and vegetables should be freeze dried when they are in season and fully ripe.
3. Avoid freeze drying foods that won’t taste good reconstituted. Berries and apples don’t need to be reconstituted – the freeze-dried version of these fruits tastes good as it is.
Freeze dried meat or spaghetti, on the other hand, will need to be reconstituted with moisture in order to be edible. Don’t freeze dry foods for which this won’t be possible.
4. Process the food for freeze drying. Get the food ready to be preserved by doing the following:
- If applicable, wash and dry the food thoroughly.
- Slice the food into small pieces. Cut apples, peppers, potatoes and other fruit and vegetables into small chunks, so that the moisture is easily removed.
5. Place the food on a plate or tray. Spread it out so that the pieces of food are not clumped together.
6. Place the tray in the freezer. If possible, make sure the freezer is empty of other items.
- Don’t open the freezer much while the food is freezing. This will slow the freezing process, and cause ice crystals to develop on the food.
- If you have a deep freezer, use it. The food should be frozen at the lowest temperature possible.
7. Keep the food in the freezer until it has freeze dried. Over the course of about a week, the process of sublimation will take place, and all of the moisture will be removed from the food.
Test to make sure the food is completely freeze dried by removing a piece and allowing it to thaw. If it turns black, the food is not freeze dried yet.
8. Store the food. Once the food has completely freeze dried, place it in freezer storage bags. Push out the air, seal the bags, and store them either in the freezer, in your pantry, or in your emergency preparedness kit.
Other methods of freeze drying involve using dry ice and vaccum chambers.