What Is a Freeze Dryer?


Quick Answer

A freeze dryer is a machine that dries food by subjecting it to low pressures and extreme cold. This simultaneously preserves the food, kills any microbes present and makes the food lighter to carry.

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What Is a Freeze Dryer?
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Full Answer

Freeze-drying originated as a preservation technique with the Inca, who stored food on cold mountain tops where the low air pressure and extreme temperatures caused the moisture inside the food to evaporate. However, the first freeze-drying machines that were invented in the late 1800s were not based on Incan technology.

The first freeze-drying machines were developed using a special laboratory apparatus that used a vacuum pump to create a local low pressure area. The low pressure was meant to draw out liquid from lab specimens, but the process did not work unless the specimen was first frozen.

As of 2015, freeze dryers are commonly used to preserve lab samples and pharmaceutical products, as well as meat, vegetables and fruit. Freeze-dried food is popular with hikers because it does not need to be refrigerated and is lighter than other kinds of preserved foods.

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