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I've been considering buying a food dehydrator, mostly for fruit, maybe some jerky. I know that a conventional food dehydrator can take a while, 12-24 hours. I'm curious, can I use a vacuum chamber to dehydrate the fruit instead? Will it take less time? I imagine that making raisins may be problematic as they have a sealed skin and would explode, but I don't think that would happen with banana or apple slices.

  • Definitely doable. You'll need a decent vacuum pump, perhaps $400: google.com/search?q=vacuum+pump&ie=utf-8&oe=utf-8 Also needed, some sort of vacuum chamber with shelves. If you're mechanicaly inclined, that can be DIY:google.com/search?q=vacuum+chamber&ie=utf-8&oe=utf-8 Finally you'll need a cold trap to keep the sublimed water out of your vacuum pump oil: google.com/search?q=vacuum+cold+trap&ie=utf-8&oe=utf-8 These tend to be pricey, and run on dry ice/acetone. Maybe someone's come out with a cheap -70°F freezer? Project could easily get very expensive. – Wayfaring Stranger Jan 27 '15 at 4:16
  • By vacuum chamber do you mean something like a vacuum packer? Instead of what the comment above suggests? – Doug Jan 27 '15 at 7:50
  • Not a vacuum packer, I have access to a vacuum chamber. But I'm not thinking about a freeze dryer, either. Just a straight vacuum chamber with no refrigeration. – viggity Jan 27 '15 at 14:07
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    "access to a vacuum chamber" - one of the problems with using lab equipment for food is that you don't know what has been put into that chamber. If a lab was using pathogens or toxins in it, you don't want residues to contaminate your food. – rumtscho Jan 27 '15 at 16:17
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    eBay has lab grade "Vacuum Aspirator" that can develop 29.5" of vacuum. That way you will not need a "Cold Trap" or a mechanical pump. Once the vacuum is applied to your chamber you may be able to shut off a valve to the aspirator, to save on your water bill. – Optionparty Jan 28 '15 at 0:27
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You can certain lyophilize fruit. It's done commercially and there's no insurmountable barrier to doing it at home. Since water basically 'boils til it freezes' in a vacuum, then slowly sublimes, you're not likely to get much improvement on a dehydrator's 12-24 hour cycle. For some fruits however, product can be much better when freeze dried. Here's some examples of what you can get: Bananas, peas, tomato slices, carrot slices, spinach, beans, mango, whole berrys etc.

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