In the history of food, one ingredient stands above all others in terms of its importance to the development of civilisation.

Salt.

This unique edible rock enabled the rise of the modern city, gave explorers their freedom, and was the foundation stone for the concept of an economy. Salt has funded terrible wars, and also funded great art.  Indeed, until the 1950's salt was the most widely traded food commodity in the world. In quantitative terms, the world still consumes billions of tonnes each year.

But it's not all rubbed on the rim of margarita glasses or sprinkled liberally on fish and chips. In fact the single largest use is not for food at all, but rather for de-icing roads over the long Northern winter. This is possible because salt affects water in a very special way. Critically, salt lowers the freezing point of water, which helps melt ice and prevent ice formation. Partly it achieves this by attracting the water due to their chemical interaction. Salt is a water magnet.

It is this natural connection between water and salt that made salt so vital in history. Salt enabled the preservation of food.

In an era when refrigeration had not yet been developed, and the cost of transport made long-distance trade difficult, preserving food was the key to survival. The bounty of Spring and Summer did not continue into the cold and dark months, hence families could only survive on what they had laid aside ready for use.

Salting food has three effects. It draws out some moisture, concentrating the flavour. It prevents the formation of bacteria, as salt is antiseptic - this means that the food may last a very long time. But it also renders the food very salty, sometimes to the point of being unpalatable.

Many food have been salted - vegetables, meats, fish, and even poultry. But the most famous is gravalax.

Traditional Swedish cured salmon was saltier than the sea itself. Wrapped in a thick blanket of salt, the fish would be buried in the earth for up to three months. 'Gravad' means buried (think 'grave'), 'lax' means salmon.

But when it was unearthed the gravalax would require significant soaking in water to become appetising again. So modern chefs adapted the traditional recipe to reflect modern tastes and the availability of refrigeration. The salt has been cut considerably, and some sugar is added to help with curing. The resulting flavour is milder and more delicate, although the fish will remain fresh for a shorter time.

The reduced storage time doesn't have to matter, though. Find some pumpernickel bread, pickles, horseradish and mayonnaise, then dig in. Now that's civilisation!

See Fast Ed's Gravalax recipe.

See all of Fast Ed's recipes.

This article was kindly provided by Fast Ed. It first appeared in The Manly Daily.