Tannins are high molecular weight compounds derived from polyhydric phenols. The components have the ability to precipitate proteins and alkaloids, endowed with an astringent effect.
Tannins are called so because of their properties. They are able to "tan" the skin, make it waterproof. Previously, oak bark was used for this . The process, in this regard, began to be called "tanning", and the substances themselves - tannins. The components are low toxic.
It should be noted that tannin (tannic acid) was first obtained in 1797. In its pure form it was produced in 1815.
Tannins are widely used as astringents, bactericides in diseases of the digestive system. In addition, components are used for inflammatory diseases of the oral cavity (as rinses), ulcers and other lesions.
The anti-inflammatory activity of tannins is related to their ability to interact with proteins. As a result of this, a protective film is formed on the mucous membranes, preventing the further spread of inflammation. Tannins are effective when applied topically as hemostatic agents.
A large enough amount of tannins is present in tea. Some components, as already mentioned above, have hemostatic, bactericidal and anti-inflammatory properties. (Sleeping tea leaves, for example, is often used for eye diseases). Individual polyphenols (catechins) possess the properties of P-vitamin. They help improve digestion, strengthen the walls of blood vessels of different calibers, reducing their permeability. It is worth noting that green tea has a full range of catechins . In black, these polyphenols are much smaller.
Tannins actively interact with an acidic environment and iron. So, for example, when brewing tea in an iron container, a brown and cloudy tea leaves is obtained. An acidic medium brightens tea (this effect can be seen by adding lemon to it). The more tannins in tea, the more astringent and astringent its taste will be. You can soften its taste by adding milk.
Tannins are best dissolved in hot water (therefore, tea is brewed in boiling water). Cooled tea leaves often become cloudy - this is one of the properties of polyphenols. If this does not happen, then this indicates an insufficient amount of tannins in the raw material. The clouded tea leaves can be heated - then it will become transparent again.
The properties of tannins are actively used in medicine. Tea polyphenols, for example, are known to be powerful antioxidants. In this regard, they are often used for poisoning. This is due to their properties to form safe compounds with various harmful proteins, acids, alkaloids, metals and then remove them from the body.
In nature, many plants contain tannins. Most of these compounds are in dicotyledons. Tannins are rich in algae, mushrooms, ferns, mosses. There are tannins in pine, willow, and beech.
Tanning sumy - a representative of the sumac family - also contains polyphenolic compounds. It should be noted that young shoots and leaves collected before the formation of green fruits are of the greatest value. A decoction of raw materials is prescribed for vomiting, nausea, hemoptysis. Infusions are widely used for inflammation in the oral cavity, larynx, pharynx, nose. In addition, tannin from sumac is used for burn diseases, wounds as an astringent, antiseptic and anti-inflammatory agent. The effectiveness of decoctions, tinctures in the initial phase of diabetes mellitus has been established.
At the same time, powdered dry sumac fruits in the Caucasus are used as a hot seasoning for meat and dishes from it.