How do they freeze dry fruits?!


Question:

How do they freeze dry fruits?


Answers:
Freeze-dried fruit is made by a freeze-drying process which is simple in concept but involves complex technologies and, therefore, is quite expensive.

Fresh fruit is frozen and then placed in a drying chamber under vacuum. Heat is then applied to the shelves inside the chamber on which the fruit is sitting; under this condition, water is evaporated from the fruit while it remains frozen (called sublimation process). The evaporated water vapor is then condensed onto freezer coils at the bottom of the chamber.

The freeze drying process is done when the water has been completely removed (<1% moisture). In this dry environment, no microorganisms can survive. All enzymatic activities stop in this condition as well. Thus, freeze-dried fruit can be kept for years with no noticeable change in taste and other qualities once it's sealed in a moisture-free package.

Normally, it takes about more than 10 pounds of fresh fruit to produce 1 pound of freeze-dried fruit because water makes up 80-90% of fresh fruit weight

The botanical items are frozen and then placed under a deep vacuum. Under these conditions moisture in them (in the form of ice crystals) will sublimate directly into water vapor, which then migrates into the condenser and is removed from the system. When sublimation is complete, the freeze dried botanicals can be removed.

Go to this site and look around there are some videos of past shows. Chances are there is one and freeze dried fruit or something similar. It's a show on the discovery channel.
http://science.discovery.com/fansites/ho...

Hope you find it




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