Pemmican made in this way keeps mainly because it is dry (see drying). Salt played no part in the original drying process, though it might be added later for flavour. The berries were probably also added for flavour, but had a useful effect because of their content of benzoic acid, a natural preservative, which represses the growth of micro-organisms. The fat also helps preservation by sealing the meat from the air. The skin wrapping is not a sterile container because the food is not cooked in it—in fact, the only heating is the melting of the fat—but at least keeps the contents clean.