Tea enthusiasts have undoubtedly noticed that the infusion colors of the six major tea categories vary significantly. While some may appear similar, there are distinct differences. Have you ever wondered why this happens? The answer lies in the composition of tea polyphenols, which play a crucial role in determining the color of tea infusions. In this blog, we will explore the science behind the captivating colors of different tea infusions.
Understanding Tea Polyphenols
Tea polyphenols are vital components of tea leaves, comprising primarily flavanols (mainly catechin compounds) and flavonoids. The primary water-soluble constituents of tea polyphenols that contribute to the color of the tea infusion are catechins, flavonoids, as well as oxidized polymers like theaflavins, thearubigins, and theabrownins.
Catechins: These compounds are originally white solids but undergo oxidation in the presence of air, turning into yellow-brown substances. Teas with higher levels of catechins exhibit lighter colors.
Flavonoids: Also known as flavones, these compounds are naturally pale yellow, resulting in a green-yellow hue in the tea infusion.
Oxidized Polymers: The yellow theaflavins, red thearubigins, and brown theabrownins are formed through the oxidation and polymerization of catechins. These contribute to the various shades of yellow, orange, and brown observed in tea infusions.
Tea Types and Their Infusion Colors
Green Tea: Green tea infusions typically appear pale green with a slight yellowish tint. This color results from water-soluble pigments like flavonoids and flavones present in the tea leaves.
Black Tea: Black tea is classified as fully fermented tea. Its infusion appears red due to the formation of theaflavins, thearubigins, and other oxidized polymers during the fermentation process. The dominant presence of thearubigins, which have strong coloring abilities, imparts the rich red color to black tea infusions.
Oolong Tea: Oolong tea lies between green and black teas in terms of fermentation. As a result, its infusion color varies. Some oolong teas may exhibit a greenish-yellow hue, while others may have a reddish-brown tint.
White Tea: White tea, with minimal oxidation during processing, generally has a light and delicate infusion color, leaning towards pale yellow.
Yellow Tea: Yellow tea undergoes a unique processing step called “smothering” or “sealing yellow.” This process imparts a yellowish hue to the tea infusion, which sets it apart from other tea types.
Pu-erh Tea: Pu-erh tea is unique in its fermentation process. For ripened (shou) pu-erh, the prolonged fermentation leads to further oxidation and polymerization, resulting in a deeper color, often described as burgundy or reddish-brown.
The diverse colors of tea infusions can be attributed to the varying levels of catechins, flavonoids, and oxidized polymers present in different tea types. From the light green-yellow of green tea to the rich red of black tea and the deep hues of pu-erh, each tea offers a distinct and delightful visual experience. Understanding the science behind these colors enhances our appreciation of the art and science of tea preparation. So, the next time you enjoy a cup of tea, take a moment to observe and savor the unique infusion color that each tea has to offer.