Decade potato

NASA famously freeze-dried ice cream so that astronauts could enjoy it in space. But this method of food preparation actually dates back hundreds of years: the South American chuño, or freeze-dried potato, remains edible for decades.

Here’s the process: first you harvest the potatoes and lay them out flat, high up in the Andes. If you do this at the right time in the right place, they freeze during the night and dehydrate under the cold sun during the day. Stomp on them occasionally to get rid of excess moisture, and you have chuño.

Because a properly freeze-drived chuño remains edible for a long time, they were a staple of the Incan and Tiwanaku Empires. They are still a popular part of Bolivian and Peruvian cuisine, used in soups or ground up into flour.

• Chuño
• Freeze-drying