I wrote about the effect of salt on the boiling point of water recently and Sciencebase reader Derek Burney asked why cooks use salt when boiling vegetables, for instance, if the effect on boiling point and so cooking times is so minimal, as I explained.
Well, the small amount of salt (sodium chloride) added to food has very, very little effect on the boiling point and so really does not affect how quickly the food cooks. The fundamental reason we like to cook with salt is that salt has not only its own taste, but also interferes with the bitter-taste receptors on the tongue, essentially blocking them temporarily and so masking the taste of any bitter compounds in the food you eat, therefore emphasising any sweet tastes. It really is purely there as a flavour enhancer. Try it with some raw lettuce, eat a leaf raw and concentrate on the bitterness. Then sprinkle on some salt and eat the second leaf, besides the taste of the salt, you will notice it actually tastes sweeter.
Given how bitter and downright nasty some vegetables can taste raw – think Brussels sprouts, spring cabbage, turnip – and perhaps more so in days gone by when quality may have been even lower, it is easy to see why adding salt to the cooking pot would have become standard practice.
This was covered in New Scientist a while back. The sodium salt of the glutamic acid, commonly known as MSG (monosodium glutamate) does even more, it has the bitter-blocking sodium ions. It adds a frissant through the stimulating “deliciousness” (umami, in Japanese, from the word for savoury) of the glutamate. Some research indicates that there are umami receptors on the tongue representing a fifth taste sensation alongside bitter, sweet, salt, and sour. Different research again adds a sixth taste sensation to our tongues, claiming a receptor for fatty acids.
Given the highly stimulating effects of salt (as taste and bitter blocker), MSG, and fat (in the form of fatty acids) on our tongues it is perhaps no surprise then that salt-laden fatty foods taste so delicious.