Freeze-drying is a physical transformation, not a chemical one. It is a cold process that consists in freezing and dehydrating by creating a vacuum. This way, water is removed by sublimation, vaporised directly from a frozen state. No heat involved, unlike other dehydrating processes, and no chemicals added. Nutrients & flavours are retained for a long time, without the need for preservatives or additives. On average, weight is reduced by 75% between fresh and freeze-dried food, creating crunchy and nutrient-dense barks.

Considered discovered by the Peruvian Incas who were letting potatoes freeze at night and removing their water content by stomping them with their bare feet, the technology was really developed in the twentieth century as a way to preserve medicine drugs, in particular from WWII for blood plasma and penicillin, and food for astronauts. No more bare foot involved!