快猫短视频

WE CAN taste temperature as well as food鈥攂ut only in unusual
circumstances, say scientists in the US. They have discovered that rapidly
cooling the tongue leaves a sour or salty taste in many people鈥檚 mouths, while
warming the tip of a cold tongue gives a sweet taste.

鈥淚t鈥檚 a very fundamental characteristic of the taste system, but the taste
system has evolved so this normally doesn鈥檛 intrude into our daily lives,鈥� says
Barry Green of the Yale School of Medicine in New Haven, Connecticut.

In a series of experiments, Green cooled the tongues of volunteers below the
normal body temperature of 37 掳C. Some people noticed a sour or salty taste
when their tongue cooled below 20 掳C. The most common response was a sweet
taste when the tip of the tongue warmed from 20 to 35 掳C, though it varied
between people and over the tongue鈥檚 surface. 鈥淭wo-thirds of the people we
tested experienced at least one of these thermal tastes,鈥� Green told New
快猫短视频. About two-thirds could detect sweetness. The sides of the tongue
typically responded to cooling with a sour taste, while cooling the back of the
tongue tasted bitter to some people.

Taste receptors relay their signals to the brain through
temperature-sensitive nerve fibres, but scientists used to think that the
nervous system filtered out temperature responses. 鈥淚f you put cold water into
your mouth, it doesn鈥檛 taste like anything,鈥� says Robert Frank of the University
of Cincinnati, in Ohio. 鈥淭he problem is not explaining thermal taste; the
problem is explaining why we don鈥檛 normally have thermal taste.鈥�

Green thinks that the thermal taste response is normally masked. 鈥淢ost things
you put in your mouth tend to have a taste,鈥� he says. You鈥檇 only notice the
effect in unusual circumstances. For example, he suspects that after eating ice
cream, 鈥渢he rate at which your tongue warms is too slow to produce sweetness; we
do 1.5 掳C per second鈥�. You could only reproduce this effect at home if you
are naturally sensitive to thermal saltiness, he says. 鈥淚f you touch an ice cube
to the tip of the tongue, in a few seconds it starts to taste salty.鈥�