Before discussing salt, some understanding about TASTE BUDS must be presented. for many, many decades, we believed that there were only four primary taste sensations; sweet, sour, bitter and salty. Further, it was believed that these four taste elements were distributed in discrete taste bud positions in the the mouth. However, in 1908, a Japanese scientist discovered that there was a FIFTH taste which he called, "UMAMI, which was interpreted to mean, "savory", "meaty" or "delicious". UMAMI taste is found in foods containing high amounts of the compound glutamate, the sodium salt of the amino acid, glutamic acid. Thus, we now know that there are five, not four, primary tastes. Some high glutamate containing foods are tomatoes, meat, mushrooms, soy sauce, Asian fish sauce, Parmesan cheese, etc.
In addition, in spite of what we thought about taste buds being "mapped' in specific positions in the tongue, it has been found that taste buds are distributed throughout the palate, although some areas may be more sensitive than others. With this as background, we can learn about how salt (sodium chloride) can influence taste and flavor well beyond just imparting a salty taste.
As you know. our enjoyment of what we eat is enhanced by a number of senses - sight, smell, touch (texture) and taste. In the case of salt, it's use can stimulate several of our senses. A piece of chocolate or a caramel with a sprinkle of sea salt on it , for example, enhances our sight appeal by presenting a contrast in color - white granules on a dark background - on what you are eating. There is a textural difference, as well - a crunch of salt against the rich, soft, melting feel of the chocolate/caramel in your mouth. Further, salt makes certain molecules in your food more volatile, so the aroma is enhanced, thus adding to your sense of smell. Regarding the sense of taste, in addition to imparting salty taste to your food, salt also depresses the sensitivity of your bitter sense perception. Thus, if your coffee tastes bitter, adding a pinch of salt rather than adding more sugar will increase your sense of sweetness. Also, a sprinkle of salt on watermelon makes the melon "taste" sweeter.The salt, itself, does not add any more sweetness to what you are eating but by "dampening" the sensitivity of your bitter taste buds, you PERCEIVE what you are eating is sweeter. Moreover. recent studies have shown that a "sensor" in the taste buds is activated, which allows the sweet taste buds to react more to glucose (sugar), when salt (rather, the sodium component of it) is present. This allows these cells to register more sweetness. This is why salt is used in candy making to make the candy taste sweeter and why salt is a part of every recipe used in making cakes and other sweet baked items.
We now know, also, for some of the reasons listed above, that the UMAMI taste component of foods containing high amounts of glutamate is enhanced in the presence of salt. One of the high glutamate foods, rich in UMAMI taste is the tomato.You know that adding salt when eating them intensifies their favor. You know, also, that adding a rind of glutamate-rich Parmesan cheese to a sauce or soup, which always contain some salt, enhances and intensifies the flavor. Now you know why.
