How does it work? I do not get it my brain won’t comprehend how you can freeze something and also remove moisture without heat
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There’s 2 ways you can do it. You can make something really cold so it takes out all the water, or you can take out all the air, causing the water to evaporate and, as a result, freezing the product.
1. When you make the air cold, it can’t hold as much water. If you cool the air down enough that it drops all of its water, and then warm it up slightly, you have really dry air. If you expose that air to something with water, that air will want to absorb the water from that object. Rinse and repeat until you take out all the water.
2. When you reduce the air pressure, the boiling point of water goes down. [Water boiling in a vacuum.](https://youtu.be/glLPMXq6yc0) This lets the water in the object evaporate, and when water evaporates, it’s absorbs energy and cools the object down.
These are both freeze drying. It’s useful because bacteria can’t work or eat without water, so you can preserve food for a very long time.
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