When a food is sliced and its cells are cut, the surfaces that are exposed to air lose some vitamin C content. The caloric value of a fresh food stays the same when it is dried, although some dried foods, fruits for example, taste sweeter because the water has been removed and the sugar is concentrated. Dried fruits and vegetables are high in fiber and carbohydrates, neither of which is affected by drying. Dried fruits and vegetables are naturally low in fat. In comparison with foods preserved by other methods, like canning, it is quite safe.
Botulism is feared in canning because the bacteria that cause it thrive in a liquid environment.
Botulism could only occur with a dried food that had been rehydrated, then left unattended long enough for bacteria to grow. Mold may form on dried food if it was not dehydrated long enough or if the container it was stored in had moisture in it. If you see or smell mold, all the food in that container must be discarded. Remember that the organisms that cause food spoilage, mold, yeast, bacteria-are always present in the air, water, and soil. It is important to observe sanitary precautions at all stages of the drying process.