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Freeze drying food is another form of preserving food. Food can last longer and is very lightweight. Freeze-dried food also retains the color and shape of the food better. It is possible to freeze dry complete meals. But, the machine required to do this is expensive, takes up a lot of space, is heavy, noisy and uses more electricity. This machine works best in a room temperature range between 45-75°F and takes about 24-48 hours drying time.
Fruits and vegetables still need to be pretreated as in traditional dehydration. Fruit color should be protected using ascorbic acid or ascorbic acid mixtures. Vegetables should be blanched. These steps help control enzyme activity that can change color, texture, flavor and some nutrients.
It is important to note that raw and cooked meat and eggs can be freeze dried. This process does not kill harmful microorganisms that can cause foodborne illness. Care must be taken in handling and labeling these foods.
Learn more from Let’s Preserve: Freeze Drying from Penn State Extension Food Preservation.
