Regular drinkers of black tea should know that a distinct "golden ring" at the edge of the tea liquor is one of the secrets indicating high-quality black tea.

The golden ring in black tea is a key factor in assessing its quality. The primary substances forming this "golden ring" are theaflavins, a group of compounds derived from the oxidation of polyphenols. These compounds, soluble in ethyl acetate and featuring a benzotropolone structure, include theaflavin, theaflavin monogallate, and theaflavin digallate. They play a vital role in the color, aroma, taste, and overall quality of black tea. Generally, the thicker and brighter the "golden ring," the better the tea's quality.

Theaflavins refer to the orange-yellow substances in black tea that dissolve in ethyl acetate. They are crucial components of black tea, significantly influencing its color, aroma, and taste. Theaflavins are the main contributors to the tea's brightness, as well as the intensity and freshness of its flavor, and they are the primary substances forming the golden ring in the tea liquor.

High-quality black tea contains abundant tea buds, with tightly rolled leaves (small-leaf varieties) or thick, compact leaves (large-leaf varieties). The leaves are dark and glossy, with numerous golden hairs. The aroma is sweet and rich, the taste is mellow and refreshing, and the liquor is bright red with a golden ring where it meets the cup. For mid-grade black tea, the bud content is lower, and the golden ring may appear less vibrant.

There are many types of black tea, and two important sensory indicators for evaluating its quality are the "golden ring" and "cooling turbidity." A golden, glowing ring at the edge of the tea cup is called the golden ring. The thicker and more golden the ring, the better the quality of the black tea.

Therefore, the primary substance forming the "golden ring" is theaflavins in tea. Most black teas we drink exhibit this "golden ring," which generally indicates high-quality tea.