Well now… Sit back and let us take you through the science of Freeze Drying!
Freeze drying, also known as lyophilisation or cryodesiccation, is a low temperature dehydration process that involves freezing the product, lowering pressure, then removing the ice by sublimation. This is in contrast to dehydration by most conventional methods that evaporate water using heat.
Freeze drying results in a high quality product because of the low temperature used in processing. The original shape of most fruits stays the same. However, when it comes to candies, they puff up and the texture is forever changed…. But for the better! Primary applications of freeze drying include biological (e.g., bacteria and yeasts), biomedical (e.g., surgical transplants), food processing (e.g., coffee) and preservation.
Freeze-dried foods became a major component of astronaut and military rations. It is what began for astronaut crews as tubed meals and freeze-dried snacks. They were difficult to rehydrate and transform into hot meals in space until NASA improved the process of rehydrating freeze-dried meals with water. As technology and food processing improved, NASA and the Military looked for ways to provide a complete nutrient profile which they did very well.