What is Salt?

Salt is something we take for granted as a condiment in many meals, but when we start thinking about what it is and where it comes from, things get a bit more complex.

In chemistry the word ‘salt’ refers to any ionic compounds resulting from an acid/base neutralisation. An ionic compound has a very strong bond between positively and negatively charged ions—and it is this strong bond that makes salt crystals form into very regular geometric shapes.

The most commonly used salt is sodium chloride, but there are many other salts. Magnesium sulphate (Epsom salts) is used to treat magnesium deficiencies both in the body and in agricultural soils. Mono-sodium glutamate (MSG) has been used for hundreds of years as a flavour enhancer and despite bad stigma, researchers have proven it has no negative medical effects. Potassium bitartrate (cream of tartar) is formed in winemaking and has a variety of uses in cooking.

Uses for salts?

Salt is one of the oldest chemicals to be produced, researchers found evidence of people harvesting salt in China as early as 6000 BC.

Its main value is in preserving food, as it makes aliments uninhabitable for bacteria, but it is also used in textile dyeing, paper production, and in making soaps and detergents.

Salts are essential for all life as they regulate water flow through cell walls. This is why salt can make you thirsty—water in the cell walls in your mouth moves towards the salt to dissolve it.Too much salt makes you dehydrated, but too little salt can cause heart, liver and kidney failure.

Where does salt come from?

All salt that we put on food inevitably comes from the ocean. Salt is obtained either by evaporating seawater, or by mining rock salt deposits. Rock salts are formed by the evaporation of ancient salt lakes resulting from changes in ocean levels. We distinguish different salts by how they are processed. Rock salts and sea salts contain different minerals that vary depending on where the salt comes from.

Unrefined sea salts contain calcium and magnesium, which give them a slightly bitter taste, and small amounts of algae that make them smell like the ocean. These impurities can be removed to produce what we know as table salt (NaCl>99%). Supplements such as iodine and iron are sometimes added to table salt, helping people with deficiencies in these micro-nutrients.

So, the next time you sprinkle salt on your meal, eat ham, or get a big mouthful of water from the ocean, think about all the wonders of this ancient commodity. —By Max Burns