Exploring Our Fluid Earth

Humans have used salt as a food preservative since prehistoric times, especially for meat and seafood. Salt absorbs the water needed by the harmful microbes that cause food spoilage, thus limiting their growth. Common examples of salt-preserved (or “salt-cured”) foods include hams, bacon, sausages, and fish fillets (SF Fig. 2.17 A and B). Many of the deli “cold cut” meats used in popular American sandwiches are salt-preserved including salami, pepperoni, bologna, and ham (SF Fig. 2.17 C). Butter and some vegetables such as cucumbers, green beans, and cabbage are preserved in dry salt or “pickled” in brine salt solutions.

SF Fig. 2.17. Example (A) of salt-preserved foods: Italian prosciutto ham

Image courtesy of Sun Taro from Wikipedia

SF Fig. 2.17. Example (B) of salt-preserved foods: American bacon, salt-cured and smoked pork belly

Image courtesy of Made20rder555 from Wikipedia

SF Fig. 2.17. Example (C) of salt-preserved foods: Salami, a type of salt-cured sausage

Image courtesy of Andre Karwath from Wikipedia

SF Fig. 2.17. Example (D) of salt-preserved foods: Salt cod on sale at a market in Nice, France

Image courtesy of Schellack from Wikipedia

Being able to preserve food allowed humans to travel long distances and survive times of food shortages—both seasonal (winter or dry-season) and catastrophic (drought, flood, etc.). Prehistoric humans could survive long cold winters by eating salt-preserved meat from their autumn hunting season. Salt also allowed humans to transport food for trade. One example of this practice can be found in Atlantic cod (Gadus morhua), which was caught in vast quantities in the northwestern Atlantic ocean basin, the Grand Banks off Newfoundland, Canada, beginning in the 1500s. These fresh fish fillets were packed in salt and air-dried for transport to Europe where they were sold as “salt cod” (known as morue sèche to the French; SF Fig. 2.17 D). Salt cod gained popularity in northern Europe and the Mediterranean and later spread to the Caribbean, West Africa, and Brazil.

The ability of salt to dehydrate and kill microbes is also why it is a useful antiseptic (a substance used to prevent infection). The antiseptic properties of salt were written about in the Compendium of Materia Medica or Ben Cao Gang Mu, one of the world’s first comprehensive accounts of traditional Chinese pharmacology (the study of medicines) in 1578. The book mentions more than forty kinds of salt as well as possible methods of salt manufacturing.

For much of human history, salt was a relatively scarce mineral. This factor, combined with its uses in medicine, food seasoning, and preservation, caused salt to become a high-value commodity. Entire cities grew up around the salt trade and wars were fought over salt. The Austrian city of Salzburg was one of several salt production and trading hubs established in Europe before ancient Roman times. Its name translates to “salt castle”. From the seventh to fourteenth century AD, salt was used as currency and even traded weight-for-weight for gold in western Africa. Ancient Roman soldiers were paid a salarium, or salary, meaning money used to buy salt. A modern English phrase describes competent soldiers and workers as being “worth their salt”.