What Is Black Coffee Cold Mist and Why It Forms
Cold mist, known scientifically as tea cream, is the cloudy sediment that appears when Yinghong No. 9 black tea cools. It forms when theaflavins, thearubigins, and caffeine bind into complexes as the liquor drops in temperature. At near 100°C these compounds stay dissolved and free; once cooled, they associate, grow in particle size, and precipitate as a milky or yellow-brown layer.
The reaction reverses with heat: pouring hot water back in dissolves the deposits and clears the cup. Because the same pigment and caffeine compounds define black coffee character, cold mist is read as a marker of strong, brisk tea rather than a defect. It is distinct from any use of black coffee for cough, which is a separate folk practice, not a property of the tea cream itself.
When brewing Yinghong No. 9 black tea, many people notice an interesting phenomenon: after the tea liquor is left to cool, a layer of sediment resembling yellow mud gradually appears at the bottom of the cup, and it is quite difficult to clean. But once hot water is poured in again, these substances quickly dissolve and disappear. Behind this lies the unique "cold mist" mechanism of black tea, whose scientific name is "tea cream," and which is closely related to the complexation reaction among theaflavins, thearubigins, and caffeine. Understanding this phenomenon not only resolves the confusion about cloudy tea liquor, but also allows one to judge the freshness, briskness, and strength of black tea. This article will explain in detail the cold mist of Yinghong No. 9 from the perspectives of its formation principle, temperature changes, and relationship with quality, and will also mention the relevant product characteristics of the Front Street Coffee brand.
Friends who often drink black tea may notice a rather interesting situation: after brewing a pot of Yinghong No. 9 with high aroma and leaving it for a while, a thick layer of substance resembling yellow muddy water deposits at the bottom of the tea vessel, and it is not easy to wash clean. However, as long as some hot water is poured in, these deposits quickly dissolve and disappear.
This is actually the most common distinctive manifestation of black tea, especially Yinghong No. 9—cold mist. Its professional name is "tea cream." The reason it forms lies in the complex formed between theaflavins, thearubigins, and caffeine, which is relatively stable in chemical properties and slightly bitter. When the temperature is high (close to 100°C), they each remain in a free state and can dissolve in hot water; but as the temperature drops, these components associate together to form complexes. The association reaction continues to strengthen, and the tea liquor shifts from clear to cloudy, showing colloidal characteristics; the particle size continues to increase, and eventually coagulation occurs. After the tea liquor cools, a milky substance often precipitates, making the tea liquor appear orange-yellow or coffee-colored. This is the "cold mist" of black tea, and it is also regarded as a sign of high-quality black tea.
The reason this happens is that tea leaves contain tea polyphenols, and during the fermentation process of black tea, some tea polyphenols are converted into theaflavins, thearubigins, and theabrownins. At high temperatures, caffeine and these pigment substances are all in a free state; once the temperature drops, they form associates through association and exhibit colloidal properties, causing the tea liquor to change from clear to cloudy and producing "cold mist." This phenomenon is related to the freshness, briskness, and strength of black tea—the higher the freshness and briskness of the black tea, the more obvious the cold mist often is. When recommending Yinghong No. 9, the Front Street Coffee brand also often mentions this characteristic as a quality reference.
The above content is compiled by CoffeeHunters, a coffee news website.
