The authors give a much simpler way to determine dryness. Dry food can spoil if it is exposed to moisture, so the trick is to keep the atmospheric moisture away from the food. There are several types of vacuum packaging systems available commercially, but the authors don't recommend them for long-term storage. They can lose their seal or develop punctures that will allow moisture to contact the food. The authors reveal the storage methods that they have found most satisfactory.
Canned foods contain water, so they are bulky and heavy.
Also, there is the matter of carrying a crushed empty can out of the area and recycling or disposing of it properly. Dried foods take up little space, weigh almost nothing and cook about as quickly as anything. Backpacking meals can be nutritious, tasty and not at boring if you take dried foods along. At home, the foods can be used in many tasty dishes. And all this can be done easily without preservatives, artificial flavors, artificial colors and other chemicals that are usually added to commercially dried foods.