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To: grumpygresh

Didn’t know that there was a freeze dryer model for home use.
I understand food freeze dryer lasts longer, ie: up to 20 yrs, as opposed to < 5 years for heat dried or other methods.
However, the $3800 spent for the home freeze dryer may not have a favorable return on investment.


8 posted on 08/24/2015 10:39:52 AM PDT by MarchonDC09122009 (When is our next march on DC? When have we had enough?)
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To: MarchonDC09122009

I’ll have to look up their patent application but I’m a bit skeptical. To properly freeze dry, the item has to be frozen and then put under vacuum at a pressure below the triple point. Typically this is about 0.2 to 0.5 mmHg. The frozen water will sublime (solid to gas without a liquid phase) over a period of a day or several days.

The big issue is that the water load is huge. This requires a condenser at about -40 to -60 deg C between the chamber and the pump. This condenser does most of the work. For very small batches dry ice can be used but large scale systems use mechanical refrigerators.

Adsorbents like silica gel or molecular sieve can also be used. But they are high maintenance and only really good for small batches.

I’ve freeze dried some vegetables just to try it. It’s energy intensive in small batches. (1/2 HP pump for a day for some banana slices.)

Again, unless they have some great new system, Mountain House #10 cans are a great deal.


11 posted on 08/24/2015 10:50:23 AM PDT by NewHampshireDuo
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