Why do you think "astringent"?

"Why do you think?

astringent" Beijing News weekly of the new knowledge

Daily language often combined with the "bitter".

However, in fact, the "bitter" and "astringent" basically. The "bitter" is a kind of pure taste, from the tongue of taste cells feel. The "astringent" widely accepted definition is certain substances generated within the mouth dry, shrinkage. Can lead to "astringent" sense of many, one of the most common is called the "tannins". It in many plant foods are the most typical is a red wine and tea. Many have no ripe fruit contains a large number of persimmon tannin, for example. We use the "burn" to describe the immature, but it has a biological basis of knowledge.

We know what they can produce "astringent" know what they can affect the perception of the "investigation", but "astringent" what, scientists have not yet reached consensus.

There are experimental, and tannic acid oral epithelial cell direct action taken as a result of some neural responses. There are also some experimental investigation on the matter can be found like salt and acid that changes cell membrane potential, and later found to exist only on tannin responsive neurons. There is evidence that these scientists, astringent and bitter salty sweet and sour, is a kind of taste.

However, more people do not agree with this conclusion.

They think "astringent" is a kind of sense. Support for this view of direct evidence is lacking in the mouth taste receptor sites, still be able to sense the "investigation". Tannin into oral, and saliva protein binding generates insoluble sediment. Tannic acid and protein between this reaction accompanied by mouth tissue dehydration and permeability decreases. Further, they think this kind of reaction can cause shrinkage of salivary duct, or even close, resulting in a dry, contraction of "astringent" sense. But such a change, by the mouth of the mechanical sensors to perception.

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It should be said that the two theories is not sufficient, we cannot fully explain all the experimental phenomena.

For example, according to the theory, if you increase the sense of touch food of viscosity, then the same concentration of investigation on the matter of "investigation" will be reduced. Tannin is true, but some other investigation on the matter are not affected. "Astringent" what is it not that important, or go to look at something else, such as why do the same thing, some people find it very "astringent", some people don't feel so hard? someone studied the saliva in the protein content and investigation, found that the protein content of higher for less astringent for sensitive. Another study found that those words more people, more pleasure under investigation, but the duration will be slightly shorter, more weak intensity. In 2009, Italy scientists discover, saliva-recovery capabilities of this group of people more susceptible to Shibuya, the same concentration of tannins solution they would feel more "hard". Does this mean when your mouth more saliva, taste of the investigation is more light, but if you just have mouth rinse, saliva compare light so the taste of the investigation will be strong? everyone can try.

This is a wonderful evolution: plants contain tannin, immature fruit especially high in content, but many mammals you can feel "astringent" this bad taste.

This is a bit of a struggle against each other, mutual compromise. From today's situation, tannin is a kind of "anti nutritive substances", affect other nutrient absorption, intake also poisoning. This plant can be counted as a protection mechanism. For including people, many animals, the investigation has the role of the "warning" — "fruit has not matured," and "eat dangerous animal!", such as squirrels on tannin would not haughty, according to eat. While the birds, you simply can't to astringent sensations, but also can feel like eating eat. Perhaps in order to make your own seed spread farther, so plants prefer birds, it is also possible to eat seeds, bird deliberately evaded the astringent sensations ...

It should be noted that some studies found that there seems to be a certain amount of tannin health value — this becomes a business people advocating "tannin health".

However, even these beneficial effects are the final confirmation, it does not overturn the tannin those "anti nutrition" performance — this is just a matter of both sides.

Wine, especially red wine contains a large amount of tannin, it generated investigation is one of the characteristics of the wine.

Tea also contains a lot of tannin, tea is astringent. The existence of sugar can reduce investigation, so even if the tannin concentration, dry wine will be more than dessert wine astringent. Tea with sugar, can also reduce astringent sensations.

□ Cloud Centerless (United States Food Engineering doctorate)