Freeze Dried Foods: What, Where & How?
What are freeze dried foods, and how is it done? Where can you get good quality freeze dried foods? What: Simply put, freeze drying dehydrates food or other substances to increase their shelf-life. How: Freeze drying works by first freezing the food, reducing the pressure by applying a partial vacuum, and then adding just the right amount of heat to cause the solid (in this case ice) molecules to jump to from a solid state to a gaseous state skipping the liquid phase altogether. As you can imagine there's a balancing act between too little and too much heat. Too much heat and ice turns to water. Too little heat and the ice can't make the jump from a solid to a gas. They may also have more nutrition than the same food that's been heat dehydrated, if the dehydrated food has been dried at a high temperature. Although there are now food dehydrators available that allow for adjustable low and high dehydrating temperatures. The temperature required can also vary with the type of food being dried, i.e. meat.
Pros: Freeze drying usually does a good job of leaving most aromas and flavors intact. Freeze dried foods, like dehydrated foods, can be kept for long periods of time without refrigeration and weigh much less than the same fresh water-rich food it started as. Cons: Not something you can usually do yourself. More energy intensive than dehydrating. Where: Some of the better quality freeze dried foods can be found at two of the best online gear stores I've found, Backcountry Mountain House Rice and Chicken
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