Freeze-drying or lyophilization. During freeze-drying, the berries and fruits are dried under vacuum (0.05 ATM) and very cold (up to -80 ° C). Depending on the moisture content, the temperature is slowly raised. The process can take several hours (even days) until the fruits gradually dry out. The process takes so long that the absorption of the liquid does not cause overheating, which can change the composition and structure.
During this process, the water in the berries goes to the ice and the vacuum system removes the ice from the fruit and converts it into steam without going through a liquid state. This phenomenon is called sublimation – the conversion of water from a solid to a gaseous form. It is for this reason that berries, fruits, vegetables and herbs do not change their shape, volume or color after freeze-drying. The natural taste, aroma, appearance and nutritional value (including vitamins) of fruits and herbs are also preserved.
As there is no more diluting water in the plants, only the taste of very sour and sweet berries and fruits has slightly intensified. The textures of all freeze-dried fruits become specific – airy and crunchy. By using this method, cell breakdown is minimal and the nutritional value of the food is preserved. Since the plants are dried to below 39 ° C, the fruits dried in this way are also called raw food.