Freeze-Dried vs Dehydrated
Not all food will last longer than twenty years, but there are two kinds that will: dehydrated and freeze-dried.
To dehydrate food, it is put into a heated chamber to slowly evaporate the water found within. Your food usually shrinks during this process, as well as changes the texture, color, and flavor somewhat. Since the product’s size is reduced, more food can fit inside a can. Dehydrating food is also cheaper than freeze-drying. Commercially dehydrated products typically have less than 5% moisture, making them a great long-term option.
The freeze-drying process, on the other hand, uses sublimation (think dry ice) to remove the water. Food is flash frozen and then put into a vacuum chamber where the temperature is raised and lowered to turn the frozen moisture into steam without melting. The moisture is then sucked out through a vacuum. After food is freeze-dried, the product retains its original size, texture, color, and flavor. This is a more expensive process than dehydrating, but you end up with a product that has greater amounts of nutrients and less than 2% moisture, giving it even longer shelf life.
Baking mixes come only in dehydrated form (freeze-drying it just won’t work). But most everything else can be freeze-dried. When buying your food storage, buy items that you like. This also prevents food fatigue. You may love whole wheat bread, but you’ll be pretty sick of eating it every meal for a week or longer.