Salt as a preservative

Historically, whether food was hunted, gathered, or grown and harvested, food supply was rarely available year-round to all members of a society. Yet, effective, year-round, reliable food storage was vital, especially for non-nomadic agricultural societies. Today, to maintain reliable food supplies to our ever-expanding urban populations, we refrigerate, freeze-dry or can our food. Food preservation problems seem trivial to most consumers in the developed world, outside of the world’s war zones. But, prior to the 19th century, effective food storage often made the difference between life and death to large segments of the world’s human population.

In arid climates, food can be effectively stored by drying. But in more humid temperate climates, fungus and bacteria rapidly destroy stored and cellared food. Even where food can be stored in winter ice, it quickly rots when spring thaws set in. 

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Nick Brandt unexpectedly found the dead animals that had washed up on the shore of Lake Natron in Tanzania, preserved by the high content of salt in the lake. He posed them as they had been in life. The photographs, taken between 2010 and 2012, appear in Brandt’s book Across the Ravaged Land (available from <http://www.nickbrandt.com>).

Documents from northern Europe, give some clues about the severity of the problem, and its solution. In medieval societies, with relatively poor transportation systems, villages and counties had to be close to self-sufficient in food. If a bad harvest occurred, then to mitigate a potential disaster there had to be enough food stored to tide over until the next harvest. Medieval Europe offers an example of the way in which agricultural societies dealt with food security. Good-quality arable land was scarce, and had to be used for crops. That meant that grazing and foraging animals, mainly cattle and pigs, were turned out into the local woodlands for the summer to forage for grass, roots, and nuts. Any relative shortage of winter fodder in turn meant that surplus animals would best be butchered before cold weather drove them indoors. In medieval England the annual slaughter was traditionally around Martinmas, St Martin’s Day (10 November), but it was earlier in the colder climes of Sweden. In turn, that meant that fresh meat was readily available only at that time, and that fresh protein in the form of milk and butter was only available in winter from cows kept in shelter. In addition, taxes were often paid in kind rather than money, and that meant that the landlord had to be given foodstuffs that could be stored.

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Salting fish for its preservation

The response of the Swedes, and most northern Europeans, was to preserve almost all their food, and they used salt to do so. Beef and pork were salted and dried as joints, hams, and sausages. Butter was salted. Typically it took a pound of salt to preserve 10 pounds of butter (salt was sufficiently costly that housewives removed salt before they used stored butter). Fish, whether freshwater or from the sea, were salted and dried, and bread was salted and hung to dry. Surviving records from 1573 show the servants of King Gustavus Vasa of Sweden ate some 102 kg (224 pounds) of beef and pork, but 99 kg of it (218 pounds) was salted and dried. They seldom had fresh meat. For example, in 1573 the King issued an order to release 3-year-old butter from the tax stores for some men hired to work at the castle, and ordered the sale of 4-year-old (barley) malt because it was starting to get weevils in it. He ordered the peasants to store their butter and meat in the fall, after the annual slaughter, but he also ordered them not to eat any of it for 12 months (as they should be eating the previous year’s food during that time).

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Medieval salt production on Læsø, Denmark (reconstruction). In the Middle Ages, the island was known for its salt industry (from Wikipedia). The ground water can reach over 15 percent salt, and this was naturally concentrated in flat salt meadows during the hot dry summers. The final concentration, carried out in hundreds of salt kilns, consumed large amounts of wood. Eventually the island became deforested, sandstorms buried villages, and salt extraction was banned. Since the end of the 1980s it has been resumed on a small scale as an archaeological experiment and a tourist attraction.

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Ruins of a Roman-era fish-salting factory, Tarifa, provincia de Cádiz, en España (source Wikipedia commons)