The Difference Between a Freeze Dryer & Food Dehydrator

Freeze-Drying Process

• A freeze dryer slowly removes water and moisture from foods placed inside. Temperatures inside the machine reach as low as 50 degrees Celsius, createing a vacuum effect. The foods inside freeze as the temperatures drop and become dehydrated as the machine sucks out all moisture from the food. Manufacturers seal the food in plastic or foil containers before sending to stores. The military, space program and other government agencies use freeze-dried products because the foods are lightweight. Astronaut ice cream is one example of freeze-dried food.

Food Dehydration

• A food dehydrator also removes liquids, such as water from the foods, but uses a different process. In the wild, foods exposed to hot sun in a sufficiently dry climate slowly dry out without spoiling. Manufacturers use large machines that have air constantly revolving and moving both under and over the food. The wind creates suction, which slowly pulls the moisture out of the foods. Beef jerky falls under the category of dehydrated food, though some manufacturers retain more of the natural moisture in the meat, which leaves the beef jerky more tender and palatable.

Freeze-Dried Advantages and Disadvantages

• Freeze-dried foods retain the texture, nutritional value and taste of the food. The foods cook quickly with just a small amount of boiling water. Freeze-dried foods are more expensive than dehydrated foods because the process takes so long and involves a lot of effort. Home cooks cannot freeze dry foods at home. The foods must reach a low temperature and stay at that temperature for several hours. These conditions cannot be achieved with equipment available for home use.

Advantages and Disadvantages of Food Dehydrators

• Home food-dehydrating machines let home cooks make their own dehydrated foods at home. The machines are inexpensive and create foods with a long shelf life that do not need refrigeration. The biggest disadvantage is that it takes longer for rehydration of the foods. You must place the foods in hot water and let soak for up to two hours before it reconstitutes. However, some foods, such as dried fruit, do not need to be rehydrated before eating. Also, vegetables for soups and stews can rehydrate in the dish as it cooks.