There’s a fairly common misconception that the terms “dehydrated food” and “freeze-dried food” are the same. Knowing the difference will help you decide how to store and preserve food for your family.
History of Dried Foods
With any type of food preservation, moisture needs to be removed from the food. Ancient civilizations discovered this and developed the early systems for drying foods that we still use today. Dehydrating is said to have been in practice since 12,000 B.C. Roman and Middle Eastern populations would dry fruits and vegetables in “still houses,” using fire to dry out and smoke the foods.
By comparison, freeze drying is a relatively modern process, though it is said to have started with the Inca Empire. Much more recently, the freeze drying process was refined during World War II as a way to preserve blood plasma, medicine, and eventually food for the troops.
The Difference Between Dehydrating and Freeze Drying
The main objective with food preservation is to remove moisture so that the food doesn’t decompose or grow mold. Removing moisture without destroying the food’s basic composition adds to both shelf life and the nutritional value of the food.
Dehydration in poorly built home dehydrators removes about 70 percent of the water in foods. In this situation, the food is only good for a few months. However, upscale commercial dryers can remove as much as 90 to 95 percent of moisture content. In contrast, home freeze drying with a Harvest Right unit removes 98 to 99 percent of the water in food.
Because of the amount of moisture that remains in dehydrated food, most dehydrated products done at home like dried fruit, meat, and vegetables have a shelf life of one to two years at most. Those same foods preserved with a freeze dryer have a shelf life of 15-25 years.
Furthermore, the nutritional value of dehydrated food is around only 60 percent of equivalent fresh food. This loss is largely due to the heat used during dehydration, which breaks down the food’s vitamins and minerals. However, according to the American Institute of Cancer Research, freeze-dried foods retain the vast majority of the vitamins and minerals found in their original state. In fact, freeze-dried food typically retains 97 percent of its nutrition because of the cold vacuum process that is used to extract the water.
Freeze drying doesn’t change the look or the taste of the food. The above freeze-dried turkey dinner includes big slices of turkey, mashed potatoes, gravy, stuffing, and corn, that looks and tastes the same as if it had just been made fresh. And, the best part is you wouldn’t know if this meal had been freeze dried 15 years ago.
What preservation methods have you tried before? What went well, what didn’t?