Ever wondered what kind of food the astronauts eat? Official astronaut freeze-dried ice cream, that's what! Enjoy your ice cream just as the
astronauts do - the freeze-dried way. Freeze-dried ice cream, as well as other freeze-dried food items, has been aboard space missions since the early Mercury missions. They continue to be used on NASA missions today.
Freeze-drying, or lyophilization, removes water from the ice cream by lowering the air pressure to a point where ice shifts from a solid to a gas. The ice cream is placed in a vacuum chamber and frozen until the water crystallizes. The air pressure is lowered, creating a vacuum, forcing air out of the chamber; next heat is applied, vaporizing the ice; finally a freezing coil traps the vaporized water. This process continues for hours, resulting in a perfect freeze-dried ice cream slice.
The application of high vacuum in freeze drying sublimates ice much more quickly which makes it useful as a deliberate drying process. A cold condenser chamber and condenser plates provide a surface for the vapor to re-solidify on. These surfaces must be colder than the temperature of the surface of the material being dried, or the vapor will not migrate to the collector.
Temperatures for this ice collection are typically below -50 °C. The greatly reduced water content that results inhibits the action of microorganisms and enzymes that would normally spoil or degrade the substance. If a freeze-dried substance is sealed to prevent the re-absorption of moisture, the substance may be stored at room temperature without refrigeration, and be protected against spoilage for many years. Freeze drying tends to damage the tissue being dehydrated less than other dehydration methods, which involve higher temperatures. Freeze drying doesn't usually cause shrinkage or toughening of the material being dried, and flavors also remain virtually unchanged.
Milk fat, nonfat milk, corn syrup, strawberry puree, whey, cocoa (processed with alkali), stabilized and emulsified by mono and diglycerides, guar gum, cellulose gum and carageenan, artificial flavor, and vegetable annatto color - are all the ingredients used in the making of freeze-dried ice cream. This is basically a brick of dehydrated ice cream, in the usual three Neapolitan flavors. When you bite into the brick, there's a soft crunch, and once the ice cream starts to dissolve in your mouth, it really does taste like chocolate, vanilla and strawberry ice cream. Its aroma is a very, very weak Neapolitan ice cream smell.
Freeze-dried ice cream is also popular and convenient for hikers because the reduced weight allows them to carry more food and reconstitute it with available water. Freeze drying is used in the manufacture of instant coffee as well as some pharmaceuticals. In high altitude environments, the lowtemperatures and pressures can sometimes produce natural mummies by a process of freeze-drying.
Eat ice cream the freeze-dried way - it's a tasty trail treat in the traditional Neapolitan flavors.