What is the foam on the surface of the tea soup?

What is the foam on the surface of the tea soup?

When brewing tea, due to the oscillation of the water flow, the surface of the tea soup will produce foam, which is --- tea saponin. Someone compared it to the dirt produced after boiling food. When brewing tea and take it "scrape" off, in fact, it is a misunderstanding and waste.


Tea saponin is a complex structure glycoside compound. Tea saponin is bitter and spicy, difficult to dissolve in cold water, and slightly acidic between pH 5.6--5.7. Has a strong foaming power, is not affected by water hardness, it is generally foam rich taste of tea is relatively strong.


Glycosides such as tea saponin are widely found in the plant kingdom. For example, ginsenosides in ginseng are antioxidants, and allyl disulfide compounds in garlic and onions also have the effects of improving immunity and anti-cancer effects.


When making tea, you often see a layer of "foam" floating on the surface of the tea soup. What are these “bubbles”? Some people think that it is a residue of pesticides or impurities in tea, which is considered to be a poor quality of tea. But in fact, the production of foam in tea soup is mainly due to the presence of a substance called tea saponin in tea. Scientific research shows that tea saponin has antibacterial, anti-inflammatory, analgesic and other effects, so it is not only harmless to the human body, but beneficial.


Tea saponin is a kind of natural glycoside compound contained in Camellia plants. It is a mixture of oleanane-type pentacyclic triterpenoid saponins. Its basic structure consists of saponins, saccharides and organic acids. Tea saponin has the generality of Camellia saponin. It is a colorless ashless fine columnar crystal with melting point of 223~224 °C. It tastes bitter and spicy, can foam, and has hemolysis. The crystal of tea saponin is insoluble in solvents such as ether, chloroform, acetone benzene, petroleum ether, etc., and is insoluble in cold water, anhydrous ethanol and anhydrous methanol. However, it is slightly soluble in warm water, carbon disulfide and ethyl acetate, and is easily soluble in water. In methanol, aqueous ethanol, n-butanol, and glacial acetic acid, acetic anhydride, and pyridine, the solubility in the dilute alkaline aqueous solution is significantly increased.


Tea saponin is distributed in the roots, stems, leaves and seeds of tea plants, but its molecular structure is different, resulting in different physical properties. In terms of content, the content of saponin in tea seeds is the highest, while the content of tea saponin in different tea seed seeds varies from seed to seed.


What is the effect of tea saponin contained in tea soup?

  1. Tea saponin has good anti-leakage and anti-inflammatory effects, can be used to regulate blood sugar, lower cholesterol, prevent cardiovascular and cerebrovascular diseases, phlegm and cough.
  1. Tea saponin is not only a good surfactant, but also has strong antibacterial activity, especially for skin pathogenic bacteria.
  1. Tea saponin also has the dual function of resisting gastric emptying and promoting gastric motility, and has a magical effect in restoring the autonomous working ability of the gastrointestinal tract.


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