Freeze-dried and dehydrated processes remove water from foods. The vital difference is between the nutritional facts.

You will get almost the same taste, smell, and texture from freeze-dried foods. On the contrary dehydrated foods might lose up to 50 percent of nutritional value during the heating period. 

Furthermore, freeze-dried foods are easy to rehydrate, and it doesn’t take more than 5 minutes. But you have to spend 10 to 20 minutes on dehydrated food.

After items are placed in the freeze drier:

1) The material is frozen solid, which separates the water from everything around it, on a molecular level, even though the water is still present.

2) Air is pumped out of the chamber, lowering the atmospheric pressure below .06 ATM.

3) A small amount of heat is applied to the shelves, causing the ice to change phase. Since the pressure is so low, the ice turns directly into water vapor.

4) The water vapor flows out of the freeze-drying chamber, past the freezing coil. The water vapor condenses onto the freezing coil in solid ice form.

This continues for many hours, or even days, while the material gradually dries out.

5) The material is sealed in a moisture-free package with an oxygen absorber.

To keep it simple, the material is frozen and placed under vacuum. From there, it is slowly warmed, immediately vaporizing the moisture. This is how the products are able to retain their nutrients and original shape.

Foods that don’t freeze-dry well include:

• Butter
• Honey
• Jam
• Mayonnaise
• Peanut Butter
• Pure Chocolate
• Syrup

These foods don’t freeze-dry well because freeze-drying works by pulling moisture (water) from foods through sublimation. This process doesn’t work with oil-based foods, so oily foods can’t be freeze-dried.