What Is Freeze Dried Food?

Freeze dried food, or lyophilization, is the process of removing water from what would otherwise be perishable food. To do this, you freeze the food, then add heat and lower air pressure to remove the moisture. This takes many hours or even days to complete, depending on what food you are trying to preserve. Freeze drying is different than dehydrating food because dehydration only uses heat to remove water, but freeze drying takes much more moisture away, allowing the food to have a very long shelf life when stored properly (up to 25 years).

Any food that contains liquid is a candidate for freeze drying, and many candies can be transformed by freeze drying to become new forms of what they once were. Let’s focus on perishable food first, then we will touch on candy.

Fruits, vegetables, meats, cheese, meals, and other prepared foods can all be preserved through freeze drying. With most items, it is helpful to freeze them ahead of going into the freeze dryer. After setting the times and temperatures on the machine, food goes onto the trays and the machine starts the freezing process. Once the liquid in the food is completely frozen, heat is added along with vacuum pressure from the pump. Once the freeze dryer is finished, it is best to add the food to mylar bags or jars along with oxygen absorbers or desiccants. Some foods can be eaten right out of the bag, or you can add water to rehydrate them (cold or hot water depending on which item it is).

The candy process is similar, but often uses higher heat. Some candies require a pre-warm at higher temperatures before the freeze drying process, and others do not. The internal structure of chewy candies becomes crunchy because the removed water leaves holes in the candy that turn into air pockets.