What is freeze-dried fruit, and how is it made? According to Gabby Geerts, a registered dietitian at Green Chef, the freeze-drying process is unique because the fruit undergoes sublimation, in which frozen water is evaporated directly from ice to water vapor, removing 99% of ...What is freeze-dried fruit, and how is it made? According to Gabby Geerts, a registered dietitian at Green Chef, the freeze-drying process is unique because the fruit undergoes sublimation, in which frozen water is evaporated directly from ice to water vapor, removing 99% of moisture from the fruit, without ever having to enter a liquid phase. Here's how it works: "[Fruit] is placed inside a vacuum chamber where the temperature is below freezing," Geerts explains. "The temperature is slowly raised, and the solid water molecules enter a gaseous state without ever becoming a liquid." In doing so, the structure of the fruit, as well as its nutritional value, is preserved.