I have to disagree with a couple of items above.
1. Pineapple is absolutely one of my favorite fruits to dehydrate. I have been doing it for years, and can only comment that if you are experiencing some issues with sticky-ness, you may not be dehydrating long enough. I literally buy a dozen pineapples at a time to dehydrate. I much prefer the slower lower temperature method to preserve the nutrition (higher temps mean the nutrition "cooks" out.) Think no higher than 115 for almost everything, except liquids that will require higher temps to overcome the additional liquids. Which leads to
2. Yes, you absolutely can dehydrate more liquid items. I have never tried it with stock, but a favorite with kids (and adults looking for natural ways to satisfy a sweet tooth,) is to use flat sheets (not the screens) to drizzle a fruit smoothee that when dried becomes a fruit leather, or the equivalent of the grocery store fruit roll up. I should note, this is not a "juice" but a smoothee - i.e. I use my blender, not my juicer, so its a thicker more milkshake consistency to dehydrate.
3. One thing I have never had luck dehydrating is broccoli. I love broccoli. I buy it in bulk. I wish it stored better when dehydrated, but it always seems to come out as broccojerky, and doesn't rehydrate well.
Oh - one other thing. Mix the dehydrated pineapple with dehydrated strawberry, and create a dry virgin daquiri snack! Delicious! and rehydratres as an incredible ice cream topping, cake baking addition, trail side snack, etc.