FREEZE DRYING
Taking food into space comes with a whole host of challenges. How do you store food in space? How do you make food last as long as possible? These are questions that scientists have been asking since before astronauts ventured into the unknown. Freeze-drying was found to be one of the best options. The process of this extreme dehydration wasn’t invented by NASA scientists, however. It was the creation of French physician Jacques-Arsène d’Arsonval during World War II. However, it was NASA-funded research in the 1970s which developed it into the widespread preservation method used today.
Freeze-drying allows food to be preserved for longer while maintaining its nutritional value by exposing foods to a series of freezing and drying. First food is frozen solid in a freezing chamber, and then a vacuum pump is used to lower the air pressure within. Along with a little bit of added heat, this combination of the freezing temperature, low air pressure and then heat causes the frozen water content of the food to escape directly as vapour, bypassing its liquid state, known as sublimation. The process takes several hours, and once completely dried out the food is packaged in moisture-free containers to prevent rehydration.