For thousands of years, philosophers have argued that water has no taste. According to them, the taste of water is the basis for other tastes. It is a starting point, a reference. The effect of water on our tongue is like the effect of darkness on our eyes and silence on our ears. Aristotle, "Water, which is a natural substance, is tasteless." he wrote. According to him, water is only a vehicle for other tastes.
Today, however, scientists have begun to realize that pure water is perceived as a certain taste. Some stated that it was perceived as a bitter taste on the tongue, while others stated that it was tasteless. By the 1920s, evidence showed that the taste of water changed depending on what you ate just prior to it. If you drink a soda first, then the water will taste acidic and may be perceived as somewhat sweet. After eating some salt, the water will taste a little bitter.
In the 1960s and 1970s, Yale University psychologist Linda Bartoshuk published a series of articles on the property of water known as the "aftertaste." According to Bartoshuk, when a person eats and drinks, the person's taste cells adapt to that stimulus. If you clean this taste with water afterwards, the cells will be active again. It's like seeing a color and then looking at a white sheet of paper and seeing that color appear before your eyes (it's called an "afterimage", "afterimage").
You don't even need to eat or drink to feel this effect. A human's saliva can also affect the taste of water, Bartoshuk's findings. During the day, your tongue is washed with a little salty saliva. The saliva has no taste because your mouth is completely used to it. If you wash the saliva with water, the next sip will make the water taste a little more bitter or sour.
The claim among physiologists has been a dogma for 30 years: water has a taste; but it only occurs as a after taste or with the effect of the food/drinks before it. On the other hand, more recently, a small group of scientists claimed that the taste of water can be perceived by itself. Beginning in the 2000s, researchers demonstrated parts of the brain that were particularly water-responsive in both humans and lab rats. At about the same time, the University of Utah discovered that mammalian taste cells synthesize proteins called aquaporins that allow water to pass through the cell membrane. Aquaporins, which are also commonly found in other cells, may be a direct way for taste cells to be stimulated by water.
If water has a special taste for rats and humans, it will not be an unprecedented discovery in the animal kingdom. We know that insects can taste water. Scientists have shown that fruit flies can taste chemicals using hard awns called brissils that emerge from their wings, legs or proboscis. These capillaries connect to a series of neurons, detecting sugary and bitter tastes and changes in osmotic pressure.
Even so, many neuroscientists doubt that this mechanism is also found in mammals. "You can find a lot of people who don't believe that water has a taste. The point is," said Patricia Di Lorenzo of Binghamton University. In their lab research, they found some areas in the brainstem of mice that respond only to water, but their findings were not supported by their colleagues. "I quit this job." she admits. "If you're in a field where no one believes in you, you have to move forward."
Sidney Simon, a Duke University physiologist, relates a similar experience. He discovered some special water-sensitive cells in the gustatory cortex of mice. He explains:
There is a strong possibility that mammals have a reaction to water. No definitive conclusion, of course, just an idea.
Other research groups, however, have not come to the same conclusion. Simon thinks this may be because they only use animals that have been anesthetized. They also investigated responses only in the front part of the tongue. It may be necessary to look at the back of the tongue to find water-sensitive cells. Whatever the case, it makes perfect sense for water to have a distinctive taste, according to Simon. He ends his words as follows:
It's the most common thing in the world. 75 percent of your body! 75 percent of the planet. I mean, why not develop something like this?