What contents in black tea affect its quality?

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The chemical composition of tea is the basis of tea quality and health effects. The chemical composition of tea is composed of 3.5%-7% inorganic substances and 93%-96.5% organic substances. There are more than 30 basic elements that constitute tea organic compounds or exist in the form of inorganic salts, mainly: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, iron, molybdenum, fluorine, etc.


So far, there are more than 700 known compounds that have been isolated and identified in tea, including three natural products: protein, sugar, and fat, as well as secondary metabolites of tea trees—polyphenols, amino acids, alkaloids, pigments, aromatic substances, etc. The chemical composition of tea is a qualitative and quantitative indicator for tea quality evaluation. The content of chemical composition of tea has a great relationship with the content of fresh leaf raw materials and processing technology.

Black tea is a fully fermented tea, and the formation of its quality characteristics depends on the types of compounds contained in the fresh leaves. Among them, the most important ones that affect the flavor of black tea are tea polyphenols (especially catechins) and polyphenol oxidase. The biggest difference between black tea production and green tea, yellow tea, oolong tea, and dark tea is that withering increases the activity of enzymes in fresh leaves, and enzymatic oxidation is used in fermentation to oxidatively degrade the chlorophyll in the tea leaves. The oxidative polymerization of catechins and polyphenolic compounds, and colored substances such as theaflavins and thearubigins of raw tea, form the characteristics of black tea with a moist brown color, bright red soup, high and strong aroma, rich and mellow taste, lively and sweet, and bright red leaves.


Yunnan is the origin of tea in the world. Yunnan’s tea tree resources are not only abundant in quantity, but also rich in ingredients. Among them, the main components of tea such as tea polyphenols, catechins and caffeine are 30%-50% higher than that of small and medium-leaf species. Together with the Indian Assam species and the Kenyan species, they belong to the world's fine tea varieties.


Dianhong, made from Yunnan large-leaf species, is unique and famous both at home and abroad, and occupies an important position in domestic and foreign trade exports. In my country's tea industry, it is known as: "Yunnan Gongfu tea, with bright color and good taste, extremely fine workmanship, is famous all over the world". In 1958, it set the highest price in the international tea market for the first time.