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.
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.