Introduction

Freeze drying is a process to dry food and other items by exposing them to low temperatures and low pressures.  This effectively removes water by transitioning ice into water vapor, removing the water vapor from the food, then converting the water back into ice once it is outside the food.

Freeze Drying has several advantages over canning including a longer shelf life, a lighter transport weight, a safer preservation method (both in processing and in food safety,) a better texture and appearance.

Canned goods have a much lower shelf life than freeze dried foods.  Canned goods can become contaminated by lids and cans rusting, jars freezing and breaking, false seals and several other things that can compromise the preservation of the product.  Freeze drying can survive air leaks in the seals (though shelf life and freshness may be compromised), dropping freeze dried food will not disrupt the preservation.  There are no metal lids or cans so rusting is not a concern. Freeze dried foods have a shelf life of up to 25 years.

Canning significantly increases transport weight of food by adding water to the product.  Freeze Drying removes weight from the product and significantly lowers transport weight.  A ton of food can be reduced to about 200 pounds in weight through freeze drying.

Freeze drying is a safer method for food preservation since it does not involve pressurized canners or glass jars, or high temperatures etc.  As far as preservation goes, freeze drying will not support pathogens like Clostridium botulinum bacteria (that can survive canning if not done properly)

Additionally, freeze drying can preserve foods that cannot be canned.  For instance, you cannot can ice cream, but you CAN freeze dry it.  You cannot can bananas, but you can freeze dry them.