freeze dryed

[Clementine Lindt]

Is there a special machine to freeze dry something? I have a dehydrator... which is best?
:banana

[Green Bean]

I'm sure there is something out there to freeze dry youre food i mean its the 21st century but i prefer dehydrating my food it works for me so i'm sticking with it. ~GB

[Toolshed]

Freeze driying machines are pretty expensive and usually limited to commecial applications, though I suppose for the right amount of money, one could be had for your kitchen.
FD food definetely looks, reconstitutes and tastes better than dehydrated.

As I understand it takes longer to FD than dehydrate. As the food is frozen first the water turns to ice, then the pressure in the dryer is reduced and ice is then turned to vapor (though I don't know how) and a vaccum in the food chamber increased to pull the water vapor out.
Dehydrating food consists of using the sun, your oven or a dehydrator to heat the food and the air surrounding it causing al the moisture to evaporate.

For doing your own food for backpacking, Dehydrating is the way to go. especially in the summer when you can get a bounty of tomatoes, peppers, apples, pears, squash and other Fs & Vs for very little at roadside stands.
I find my dehydrated food lasts for several years when stored in the fridge, thogh you will hav to experiment to figure out what moisture content you need for whatever you plan to do with your food (use it immediately or store for a longer period of time)

[dperry]

As I understand it takes longer to FD than dehydrate. As the food is frozen first the water turns to ice, then the pressure in the dryer is reduced and ice is then turned to vapor (though I don't know how) and a vaccum in the food chamber increased to pull the water vapor out.


Hi, Toolshed,

All things being equal, the lower the atmospheric pressure, the lower the melting and boiling points of water. So when you lower the pressure in the dryer, it causes the ice to melt, then evaporate.

This is also why things take longer to cook at high altitude; the lower pressure decreases the boiling point of water, which means that the food is cooking at a lower temperature than normal.