Many people consider food additives a modern innovation, but humans have used preservatives for millennia. Today, it is hard to understand how precious salt was in ancient times, when it was valued partly as an effective preservative. Salted herring were exported in large quantities from North Sea fishing communities and consumed throughout most parts of Middle Europe. During the Middle Ages, feeding livestock in winter was often so difficult that only animals selected for breeding were kept alive. Meat from the slaughtered livestock was salted for consumption over the winter.
Smoking is another ancient means of chemical food preservation.
Smoked foods include bacon, kippered herring and lox. Permitted levels of such antioxidants as additives are far below levels found in smoked meat. The hot curries and chili dishes popular in the tropics, where food safety is most difficult to achieve, tend to be high in such natural preservatives. But native South Americans living on the Altoplano, in the Andes, have subsisted on a sort of freeze-dried potato for thousands of years. The plateau dwellers carry the potatoes up into areas where the atmospheric pressure is very low, the sky is usually almost cloudless and the nighttime temperatures fall well below the freezing point of water.