Pigments in tea are a type of colored substance present in fresh tea leaves and finished tea products. They are the components that make up the appearance color, soup color, and leaf base color of tea. Their content and changes play a crucial role in the quality of tea. In tea pigments, some are already present in fresh leaves, known as natural pigments in tea, while others are formed by oxidation and condensation of certain substances during processing. Tea pigments are usually divided into two categories: fat soluble pigments and water-soluble pigments. Fat soluble pigments mainly affect the color of dried tea leaves and the color of the leaf base, while water-soluble pigments mainly have an impact on tea soup. Excluding abnormally added pigments, there are two types of pigments in tea: natural pigments and processed pigments. We will introduce them separately.
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Natural pigments in tea
(1) Fat soluble pigments
Including chlorophyll and carotenoids, insoluble in water and easily soluble in non-polar organic solvents. Chlorophylls Chlorophyll is divided into two types: chlorophyll a and chlorophyll b. Chlorophyll in fresh tea leaves accounts for about 0.3% to 0.8% of the dry weight of tea. The content of chlorophyll a is 2-3 times that of chlorophyll b. The total amount of chlorophyll varies greatly depending on the variety, season, and maturity. Fresh leaves with yellow green leaves have lower chlorophyll content, while fresh leaves with dark green leaves have higher chlorophyll content. In general, green tea should have a high chlorophyll content, while black tea, oolong, white tea, yellow tea, etc. have lower requirements for chlorophyll content than green tea. Carotenoids Carotenoids are a class of colored compounds with yellow to orange red color. There are 17 types of carotenoid compounds found in tea, which are divided into two categories: carotenoids and luteins. Carotenoids, especially during the processing of black tea, undergo extensive oxidation and degradation, forming a series of pyrrolidone compounds. Omori (1978) found that during the processing of black tea, the addition of β- Carotenoids are beneficial for the color and aroma of black tea. (2) Water-soluble pigment
Water soluble pigments are a general term for colorants that are soluble in water. Generally refers to the oxidation products of anthocyanins, anthocyanins, and catechins. Dozens of anthocyanins and anthocyanins have been found in tea, which are the main water-soluble pigments in tea. Flavonoids, also known as anthocyanins, mainly include flavonols and flavonoids, which are components of tea polyphenols. It is an important component of the color of green tea soup.
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Pigments formed during tea processing
During the tea processing, various pigments are formed, which constitute the quality characteristics of tea and play an important role in different types of tea. During the processing of black tea, the oxidation of polyphenols forms theaflavins and thearubigins, giving black tea its quality characteristics. Theaflavins Teaxanthins are a type of pigment in black tea that has an orange yellow color and astringency. It plays an important role in the color, aroma, intensity, and freshness of black tea, and is also the main component of the "bright" color of black tea soup. It is the main substance that forms the "golden circle" of black tea. Black tea with high content of theaflavins has a golden color and high quality, which is extremely popular in the market. RobertsE A. H. pointed out that the evaluators' estimation of color is mostly influenced by theaflavins. The higher the content, the brighter the soup color, appearing golden yellow. The lower the content, the darker the soup color. Tea flavins form complexes with caffeine, thearubigins, and other substances, which exhibit milk coagulation at lower temperatures and are one of the important factors contributing to the cloudy tea soup after cooling. In the 1990s, nine components of theaflavins were isolated: theaflavins 1a, 1b, 1c, theaflavin, etc. Hilton and Cloughley (1980) found that the content of theaflavins is positively correlated with tea prices, and the determination of theaflavin content can predict the market price of black tea. Teaxanthin has the effects of antiviral treatment, regulating blood lipids, and preventing cardiovascular diseases, and has no toxic side effects. Thearubigins Tea catechins are a complex class of red brown phenolic compounds. The content in black tea is about 6%~15% (dry weight). This substance is brownish red in color, soluble in water, and the aqueous solution is acidic with weak irritancy. It is the main substance that constitutes the color of black tea soup and participates in the formation of "post cooling turbidity". Tea brown pigment Tea brown pigment is a type of water-soluble, non dialyzable, highly polymerized brown substance, mainly composed of polysaccharides, proteins, nucleic acids, and polyphenols. It is further oxidized and polymerized by theaflavins and thearubigins, and is an important factor causing the dark color of black tea soup. Tea brown pigment is extracted from Pu erh tea (ripe tea) through modern physical technology and has beneficial effects on the human body, such as inhibiting blood lipids and lowering blood sugar. There are various pigments in tea, many of which are beneficial to human health. However, abnormal additives and pigments from the outside can cause harm to the human body, so when purchasing tea, one should carefully choose and distinguish them.
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Do you want to add pigments?
How to identify tea in the market
Dry tea: too bright in color From the dried tea of a tea, many things can be seen, such as the aging and tenderness of the raw materials, and the quality of the processing technology. Similarly, we can also see from the dry tea of a tea whether it has added pigments. Usually, dry tea with added pigments will appear very bright, such as Biluochun with lead chromium green added, Jinjunmei with sunset yellow added, etc., which will be exceptionally bright. Aroma: impure Tea with added pigments can give it an abnormal odor. If the tea is not pure after brewing, with peculiar smell, miscellaneous smell and other difficult to identify flavor, then these tea may be added with essence or pigment. Tea soup: cloudy and unclear In general, the tea soup of tea should be very clear, with only a small amount of turbidity caused by improper craftsmanship, or a small amount of turbidity caused by multiple varieties of tea. And tea with added pigments will make the brewed tea soup very cloudy, not the usual color. Different pigments form different characteristics of tea. Understanding the pigments in tea can help us intuitively choose tea, distinguish authenticity, and drink tea healthier and enjoy life.
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2024-04-15
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