ASTRONAUT ICE CREAM SANDWICH
Freeze drying is like sending food into suspended animation. It feels dry to the touch, yet, by simply tearing open the foil outer and popping the freeze-dried block into the mouth (thereby re-hydrating it in the process) astronauts find that, more often than not, the unappetising-looking substance explodes with flavour!
The ice cream is placed in a vacuum chamber and frozen until the water crystallises. The air pressure is lowered, forcing air out of the chamber. Next heat is applied, vaporizing the ice. Finally, a freezing coil traps the vaporised water. This process continues for hours, resulting, over time in a perfect freeze-dried ice cream slice that keeps the ice cream totally intact, minus any moisture. Amazing.