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I want to make a freeze dryer to preserve fruits/foods.

I can get a vacuum chamber here: https://www.aliexpress.com/item/1005002865276963.html and i can put that into a chest freezer.

I had a look at the sublimation graph for water, and it looks like the pressure in the chamber is low enough at about -10°C

I was thinking, i could:

  • put the food (in slices) on trays into the chamber.
  • add some water absorbent crystals into the chamber
  • put the chamber inside the chest freezer and freeze as low as it could go -20°C
  • turn on the vacuum and run it until the pressure is as low as it will go
  • raise the temperature slowly to 0°C
  • enjoy tasty berries.

Will this work?

Fred
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pgee70
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  • If small quantities, it might be more convenient to just use dry ice. Then you can deal with the vacuum chamber outside of the freezer. Note that if you mess up the order of valves using the vacuum pump, you will spray oil into your chamber. In any case you will want food grade vacuum oil since oil vapours do flow backwards when the pressure is low in the absence of enough air molecules to push them towards the vacuum pump. There are are also potential issues of icing your pump from the condensates so you might need some extra filter parts. – DKNguyen Dec 07 '23 at 21:58
  • thanks for that information, very helpful. You didn't answer the question. in principle, will this proposed approach work? – pgee70 Dec 07 '23 at 22:30
  • I can't say. I work with vacuum chambers but not freeze drying. – DKNguyen Dec 07 '23 at 22:32

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