Three "elements" determine the quality of black tea

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Water extracts in tea refer to substances that can be soaked in hot water, mainly including water-soluble soup, water-soluble tea polyphenols and their oxides, caffeine, free amino acids, hydrated pectin, etc. These are the main flavor substances of tea soup. The content of water extract reflects the amount of soluble substances in the tea, marks the thickness of the tea soup, and the intensity of the taste, thus reflecting the quality of the tea to a certain extent.


The extracts in tea can be mainly divided into two categories: one is water-soluble oxidation products; the other is water-insoluble oxidation products. Today we will first talk about water-soluble oxidation products.

Water-soluble oxidation products mainly refer to theaflavins, thearubigins and theabrownins in polyphenols.

According to the "Yuncha Dadian", theaflavins are a general name for compounds with a benzophenone structure formed by the oxidative polymerization of pairs of catechins. It is an important component in black tea and plays a decisive role in the color, aroma, taste and quality of black tea. It is the main component of the "bright" color of black tea soup, and an important component of the intensity and freshness of the soup. It is also the main substance that forms the "golden circle" of tea soup, with a content of 0.4%-2%.


Theaflavins are closely related to the color of black tea soup. The lower the content, the worse the brightness of the soup color. On the contrary, it will be golden yellow.

Thearubigins are a class of reddish-brown phenolic compounds with extremely different relative molecular weights, including the products of non-enzymatic oxidation reactions between catechin oxidation products and polysaccharides, proteins, nucleic acids and proanthocyanidins.

Thearubigins are brown in color and are the main component of the "red" color of black tea soup. They are also an important substance in the concentration and intensity of the soup flavor. Its irritation alone is not as irritating as theaflavins, but it has strong astringency and a rich taste.


Theabrownin is a very complex compound that can be divided into dialyzable and non-dialyzable parts. In addition to polyphenol oxidation polymerization products, it also contains amino acids, sugars and other conjugates. Its color is dark brown, its taste is bland, slightly sweet, and its quantity is large. The light and dark taste of the tea soup is the main reason for the "darkness" of the black tea soup. Its content generally accounts for 3%-9% of the dry matter of black tea.

The quality of black tea requires the soup to be red and bright, with a strong, strong and refreshing taste, with a "golden circle". The quality of soup color determines the content and composition ratio of the above three major pigments.