Electric freezers and refrigerators, are wonderful modern conveniences, but they do fail. Dried foods can be safely stored for long periods without relying on appliances. Our ancestors used the warmth of the sun or a fire to dehydrate food. We have the advantage of electric dehydrators that are faster and more convenient. Blanching is heating the food by boiling or steaming it until it is heated all the way through to the center.
Foods contain enzymes that cause ripening.
Those enzymes must be destroyed, or the food will continue to ripen until it is spoiled. Drying does not destroy the enzymes, so they continue to work on the dried food. There are several commercial models available, and a homemade model is not difficult to build. The most efficient dehydrators have a heating element and a fan. At the beginning of the drying process, you will keep a vent or door partly open to allow the moisture to escape.