Is it possible to make your own freeze dried food?

[CountryKat]

Just curious but if not what companies have been a good source for you if you have part of your foods being of the freezed dried kind. Was not sure where to post this so please forgive me if you see a similiar question on the board.

Thanks,
CK

 

[Laureli]

I was told by an experienced hiker with a master's degree in chemistry? and who was working in the camping section of Gander Mountain, (it's the economy) that in order to freeze dry food, you would need some pretty sophisticated equipment.

any comments ?

 

[~gd]

I was told by an experienced hiker with a master's degree in chemistry? and who was working in the camping section of Gander Mountain, (it's the economy) that in order to freeze dry food, you would need some pretty sophisticated equipment.

any comments ?

Yep to do true freeze dry food you need a high capacy [sp] vacuum system and a controlled freezer. The trick is to remove the water without thawing it. Water will sublime under vacuum [it goes from a solid to a gas without ever becoming liquid water. The water vapor is sucked off and trapped by a very cold trap to protect your vacuum pumps. the process itself is pretty much self chilling to the point that you might have to add some heat to the system. the process is monitored with tempeture probes and the weight of water/ice trapped in your traps.
Many products are not really freeze dried [Dry milk or mashed potatoes come to mind] they are actually flash dried as liquids that are sprayed into a cyclone of fast moving air that dries them in seconds to minutes. The fast evaporation of the liquids keep them colder until dried than they started out as but these require a factory to produce. If the product appears to be tiny beads they were produced by flash drying. ~gd