If you're an astronaut bouncing around in the International Space Station, and you're overwhelmed by the urge for something sweet – what do you reach for? Freeze-dried ice cream or fruit of course! With it's low moisture content (and therefore less mess!) and high energy-to-mass ratio, our freeze-dried sweet treats are the perfect snack for astronauts, as well as hikers, adventurers and explorers. Flavoursome and sweet, with the same yummy creamy taste as we enjoy on Earth, but with a crunchy meringue-like texture. But how do they freeze-dry it?
Freeze drying is a process of preservation that relies on sublimation – a solid turning into gas without turning into liquid first. Imagine an ice cube instantly becoming steam and floating away without ever forming a puddle, that's what happens when we freeze dry food. It's a fast and reliable process of making food safe to travel in space, or to improve the shelf life.
The process starts by taking normal food (astronauts love ice cream!) and freezing it in a special industrial freezer, so it becomes very cold very fast. This freezer is usually around -40 °C. A vacuum pump is then placed over the food, sucking out all the air and creating a low-pressure environment. The temperature is then slowly increased but only to around -35 °C. At this temperature and pressure, sublimation occurs. Ice turns directly to steam which is sucked out with the air. This entire process can be repeated a few times until the water content of the food is approximately 1%.
Some freeze-dried food can be reconstituted by adding hot water, but our freeze-dried food, including our sweet vanilla ice cream, is better eaten as is! Or, if you don't like ice cream, our freeze-dried fruit is also delicious. You might notice the peaches or cinnamon apple wedges rehydrate as you eat them! They start out crispy and crunchy, and by time you've finished a slice it feels juicy and fresh. Perfect for a summer snack!