Freeze drying (also known as lyophilisation or cryodesiccation) is an extremely effective method of food storage. It allows food to be stored for decades, at room temperature, while retaining most of its taste and nutritional value. It is, for all intents and purposes, the Cadillac of food storage.
Freeze drying was first invented during the second World War. Serum was transferred to the front lines to help treat wounded soldiers, but the problem was that there weren’t enough refrigerators available for their needs, and the Serum would often spoil by the time it reached its destination. Freeze drying was invented to solve this problem, allowing the Serum to stay chemically stable, and even allowed for larger loads as removing the moisture made each portion much lighter in weight.
The same process can be and has been applied to food, first by the US army and NASA and now by civilians. It involves freezing food, then allowing all the moisture contained within it to sublimate (turn directly from ice to vapor). Bacteria and enzymes that decompose food need moisture, and once it is completely removed the food becomes preserved. The end result is basically instant food- durable, light weight dried food that can be returned to its original form by just adding boiling water.
There are two modern methods of freeze drying: Using a freeze dryer, and using basic kitchen equipment.
USING A VACUUM CHAMBER
Using a vacuum chamber is the easiest and most effective way to freeze dry food. The process goes like this:
1. Put the food in the freezer, and leave it there for at least 2 days. It must be fully frozen.
2. Make sure the chamber of the freeze dryer is clean and dry. Cover the chamber, and start the dryer.
3. Wait for the vacuum pump level to reach below 133 x 10-3. When it does, it is ready for freeze drying.
4. Place the frozen food in the freeze dryer.
5. Once the food has been freeze dried, put it inside a vacuum sealed bag. Reusable plastic bags can be used- just press the air out while sealing it.
DIY FREEZE DRYING
A freeze dryer with a vacuum chamber can be very expensive, and not within everyone’s budget. Luckily, with a little more time and creativity, freeze drying can be accomplished with regular kitchen equipment. Here’s how:
1. Place the food you wish to freeze dry on a perforated tray (a metal mesh of cooking rack work great).
2. Place the tray with the food in the freezer.
3. The food will freeze in ~30 minutes, and over the next week, the water will sublimate away. After a week, it should be ready. Test it: Let a piece unthaw. If it goes black quickly, there is still moisture in it. If not, they are ready.
4. Seal in air tight bags (again Ziploc bags can be used, but be sure to squeeze all the air out).
A good store of freeze dried food is durable and will last you for decades.
Good luck and stay prepared!
Read more from RamboMoe at preparedforthat.com.
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