So many recipes now demand the use of sea salt. Some even specify which brand it should be. Isn’t this a bit silly? Designer salt is so 1990s. After all, it is a very simple chemical: sodium chloride. Why should getting salt from the sea, or out of rock, make it any different?

Well, it is “natural”, they say. But that word is so abused in food these days that it means virtually nothing. Sea salt also boasts extras. According to its label, one of the most expensive brands contains “over 60 naturally occurring trace elements and minerals essential for well-being”. We can take that with a pinch of you-know-what, can’t we? These are areas of minutiae snobbery that only the sort of foodie who keeps an infrared spectroscope beside the wooden spoons could take seriously. It’s seasoning, for goodness’ sake, not homeopathy.

I thought this. Now I have to admit I may be wrong. We got some salt brands, posh and standard, invited some friends round and held a taste-test. And at the first hurdle the cheapo salt fell. We tried Sainsbury’s own-brand table salt versus the common French sea salt, La Baleine. We tasted them blind. They were both fine-ground. I expected a dead heat.

But the difference in taste was amazing. La Baleine was, well, plain salty: Sainsbury’s bitter and it seemed to fizz on your tongue. It was horrible. A look at the back of the packet suggested a possible culprit: sodium hexacyanoferrate, which is added to some salt as an anticaking agent. (Instead, try a traditional anticaking device: a pestle and mortar or the back of a spoon. Then put a lid on it.) Table salt costs about 4p for 100g. Some fleur-du-sel hand-harvested from the salt-marshes of Guérande in Brittany can cost 100 times as much. But salt was always expensive. It was left in the tombs of the Pharaohs as an offering and Roman legionaries were sometimes paid with it: “salary” derives from the Latin sal. If a soldier wasn’t worth his salt, he wasn’t worth his pay. No one knows if we started using salt because it enhanced taste, or because it cured and preserved: it’s one of those happy food alchemies where practical is pleasurable and vice versa.

Cooking without salt is difficult. It is the magic ingredient that can release flavour and even make the sour taste sweet. Remember the tequila slammer? But Raymond Blanc, the great restaurateur, says in his memoirs that we use salt with astonishing ignorance. Most of us do not even know what tolerance for salt our palates have. Whenever Blanc recruited a new chef, he made him take the salt test — “if one had a very salty palate I knew that he was dangerous”.

Blanc takes six marked glasses, each filled with 150ml of fresh water. Into the first he puts one pinch of salt, into the second two pinches, and so on until he reaches five. The last glass he leaves salt-free. He mixes them up. Then he asks the chef to arrange the glasses in order of saltiness, and choose which one was “perfectly salted”. “You will be amazed to discover that what tastes repulsively salty to you is perfectly acceptable to someone else . . . and if you’re the cook of the house, you might like to question the amount of salt you are serving up for others.” Quite.

When we tried this at home, I was very chuffed to find that my palate was slightly “better” — Blanc’s term — than my wife’s: perfectly salted was the one-pinch glass, while she went for two. Strangely, the plain water tasted quite acrid after the slightly sweet salted water. Blanc also suggests finding out what your pinch of salt weighs, so that you know exactly what you’re doing when a recipe calls for, say, 5g of salt. I tried this and discovered that I need to buy a better set of digital scales. Which will be fun.

And the salt taste-test? I gave everyone some unsalted carrot soup and some bread and five piles of sea salt. We set to it. The key difference in the salts was the texture: Maldon comes in small flakes, and everyone recognised it immediately; Cornish in large granules; Halen Mon “Diamonds of the Sea” comes in scabs, as someone unkindly put it. Saxa’s rock salt is a sort of gravel, “like you get in your knee after a skipping-rope accident”, but it is designed for salt grinders.

The most exotic was some pinky-grey fleur-du-sel made by a friend in Vietnam by drying the finest Phu Quoc fish sauce in the sun. It was pronounced disgusting by everyone except me. The salt made them all feel witty. Saxa: “If they taxed it, Gandhi would be quite relaxed”; Maldon was “something you’d happily throw over your shoulder”. The Cornish “punchy, like a mouthful of sea water”. In the end, the judges’ decision was unanimous: the Halen Mon from Anglesey was the nicest — perhaps because it is comparatively mild. By then we had all had too much salt. And trace elements, of course.

alex.renton@thetimes.co.uk

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