JOURNAL / TEA PROFILES

What are the Chemical Components in Tea?

From the perspective of modern science and analysis, most of the substances in tea leaves are organic compounds. These components form the foundation of tea and further influence the flavor of a cup of tea.

When we brew tea, we can detect many chemical components in the tea infusion. The amount and type of these substances, such as polyphenols, amino acids, carbohydrates, caffeine, and aromatic compounds, determine the overall quality and flavor of the tea.

DATE: August 05, 2025

AUTHOR: Catherine Fu

TAGS: Chemical Componets, Education

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Chemical Components

The changes in color, taste, and aroma during tea brewing come from these substances:

● Polyphenols give the tea its color and astringency;

● Amino acids bring umami and sweetness; Caffeine provides bitterness and stimulation;

● Aromatic compounds give floral and fruity notes or roasted fragrances.

These are the results of chemical transformations, as well as our efforts in tea processing.

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The Role of Caffeine — No Bitterness, No Tea

People new to drinking tea often describe tea as bitter. This bitterness mainly comes from caffeine, a natural substance in tea leaves.

Caffeine not only contributes to the bitterness of tea, but also gives it a “returning sweetness” characteristic and refreshing feeling after swallowing. It is a key reason tea is often described as “refreshing.”

However, the caffeine content in tea is generally lower than that in coffee, and due to the influence of tea polyphenols, amino acids, and other components, the bitterness is relatively milder than coffee. Depending on how the tea leaves are stored and brewed,caffeine may also undergo different chemical reactions, which may alter the bitterness and sweetness of the tea.

The Secret of Tea Aroma — Polyphenols

Polyphenols are the key to tea aroma. They are the “aromatic code” of tea. There areover 30 types of volatile substancesin tea leaves. The overall content of these in tea is much lower than that of caffeine or polyphenols, but they greatly affect the fragrance and style of the tea.

Typically, the more types and greater amounts of volatile compounds, the richer and more complex the tea’s aroma becomes.

Large-leaf tea varieties generally contain more volatile compounds than small-leaf varieties, and this is an important factor that contributes to their more pronounced floral and fruity notes. However, depending on the processing method, the expression of aroma can vary significantly.

White Tea — A Friend of Time

Every year, Seven TeaHouse's team travels to Fuding, Fujian during the harvest season to purchase white tea, which we then store in warehouses to age and sell after a few years. As time passes, both the flavor and aroma of the tea continue to transform and deepen.

Like how time enriches all things, youthful white tea matures into a smoother, more refined brew. Its fresh floral notes deepen into rich, mellow aromas. Aged white tea is prized for its soothing quality and growing rarity, especially those aged over a decade.

Our Shou Mei White Tea is smooth, rich, and deeply comforting in every steep. Learn more about our different White Teas, and visit Seven TeaHouse to order some today. Let us know how you like the taste!

Chemical Compents

From the perspective of modern science and analysis, most of the substances in tea leaves are organic compounds. These components form the foundation of tea and further influence the flavor of a cup of tea.