Is it really a good idea to store freeze dried food for a long-term survival situation? It may be an attractive proposition for the survivalist in you, but you probably didn't bargain on what exactly the process of freeze drying involves — and its price.
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The process of freeze drying plays with the properties of water within food. When freeze drying, a cooked portion of food is flash frozen under a vacuum. At low pressure, all but 2-5% of the water in the food sublimes, moving quickly from a solid to gas form. The evaporation of water in this process allows the food to maintain its shape and decrease the weight by up to 90% - a big plus for those who need to "bug out" in a hurry due to a disaster.
You can even freeze dry ice cream (pictured).
Shelf life of freeze dried food
Freeze dried foods last a little bit longer than dehydrated ones. Most freeze dried foods that you buy are sealed under nitrogen in resilient packaging, allowing for anywhere from a two to twenty-five year shelf life. Freeze dried fruits are on the lower end of the shelf life spectrum, lasting a little over two years.
Once the seal on a package of freeze dried food is broken, the shelf life clock is ticking, with most palatable for six months. There's a rapid falloff in shelf life if it's stored in a humid area.
Post-apocalyptic eating is expensive
Freeze dried foods are rather expensive - $1 to $2 per serving of a side dish like macaroni and cheese and $3 for a serving of ground beef. These are bulk prices - individually packed entrees cost $6 to $8 a piece.
One is easily looking at $10 to $15 dollars a day per person to sustain a diet of freeze dried food. Remember, this is food you might end up eating for hundreds of meals if a breakdown of society never comes.
Dehydrating food yourself is a slightly cheaper alternative, but requires a large amount of work and is far more susceptible to contamination.
The water problem
In addition to price, another problem rears its head with freeze-dried foods. Freeze dried food must be reconstituted in order to be eaten, necessitating a large (and clean) water supply in order to dine — and that's on top of the clean water you need for drinking.
Clean water will likely be in short supply in a post-apocalyptic survival scenario. Water can be boiled or stored in advance, while bleach and iodine are useful in killing pathogens like Giardia lamblia in fresh water. But that's a lot of work to decontaminate your water, and you might want to use that water for drinking rather than reconstituting up your freeze-dried ice cream.
Making matters worse is the fact that eating freeze dried food without reconstitution could hypothetically cause you to dehydrate.
The verdict: The post-apocalypse will not be freeze-dried
Surviving a long-term disruption in the food supply with freeze dried food would take enormous planning, a considerable amount of money, and one variable - a good, steady water supply. So it's probably not a good long-term solution after civilization falls.
If, however, you are concerned about preparing yourself for a small disruption in the food supply due to a hurricane or other natural distaster, storing some freeze dried food in the house might be a good idea. 72-hour food kits are sold on Amazon and in some big box stores.
In the meantime, don't forget about the canned food lying in your pantry. Canned goods are hefty, but they are safe for several years and, in the case of vegetables like corn and green beans, also contain a water supply. It might not taste good, but in a pinch, asparagus water could keep you alive.