The highest praise for a cup of Tea is its lingering sweetness and salivation, the transformation from bitterness to sweetness. So what is this lingering sweetness, and which components create such a wonderful taste? Let me unravel the mysteries of tea's lingering sweetness for you.

What is Lingering Sweetness?

Bitterness is the original flavor of tea, as ancient people referred to it as “bitter tea,” which has been proven. However, our innate sense of taste seeks pleasure through sweetness. Why then has tea, known for its bitterness, endured as a national drink throughout history? The secret lies in the lingering sweetness.

Lingering sweetness, as the name suggests, is a specific taste created by the initial bitterness followed by a sweet aftertaste in the throat. When tea touches the tongue, it is lightly bitter and sweet, leaving a long-lasting taste in the mouth. Over time, the sweetness gradually overpowers the bitterness, ending with a sweet finish. This contrast and comparison in one sip of tea creates a remarkable impact on the taste buds.

Lingering sweetness is also an important criterion for evaluating good tea. The stronger and longer-lasting the lingering sweetness, the better the quality of the tea is often considered. Compared to immediate sweetness, the transformation from bitterness to sweetness is more dramatic and gives the tea depth and character.

Why Does Tea Have Lingering Sweetness?

Why does tea have such a delightful and enduring lingering sweetness? People are divided into two camps when it comes to this question.

The Astringency Transformation Theory:

Professor Wang Yuefei, deputy director of the Department of Tea Science at Zhejiang University, is a proponent of the astringency transformation theory. In his book “Cultural and Health benefits of Tea,” he explains:

“Tea contains polyphenols, which can bind with proteins to form a non-permeable membrane in the oral cavity. This causes the local muscles of the oral cavity to contract, leading to a sensation of astringency, which is why we initially perceive bitterness in tea. If the amount of polyphenols is appropriate, they form a single or double layer of molecules, creating a membrane that is just the right thickness. Initially, there is an astringent taste in the mouth, but then the membrane breaks down and the local muscles of the oral cavity begin to recover, transforming the astringency into a lingering sweetness and salivation.”

In short, the interaction between polyphenols and proteins transforms bitterness into sweetness.

The Contrast Effect Theory:

The contrast effect theory has its own prominent supporters. Professors McBurney and Bartoshuk proposed in their 1979 article “The Relationship Between Different Taste Qualities and Stimuli” that:

“Sweetness and bitterness are relative concepts. After tasting sweeteners like sucrose, you might find water slightly bitter. Conversely, after tasting bitter substances like Caffeine and quinine, water may seem sweet. This phenomenon is a contrast effect.”

In summary, lingering sweetness is a sensory illusion created by the contrast of bitterness.

The mechanism behind lingering sweetness remains uncertain in academic circles. According to Old Bamboo, it is precisely this mystery and complexity, this nuanced taste experience, that makes tea endlessly fascinating.

What Substances Cause Lingering Sweetness?

Which specific substances in tea cause the lingering sweetness? This requires complex scientific experiments and lengthy explanations, but it can be summarized with a simple equation:

36 + 4 + 4 + 3 + 3.5 = One Refreshing Experience of Lingering Sweetness

36%

Polyphenols

Polyphenols account for up to 18-36% of the content in fresh tea leaves, imparting a bitter and astringent taste, which is the main reason for the saying “no bitterness, no astringency, no tea.” However, studies have shown that the content of polyphenols is significantly positively correlated with the intensity of the tea's lingering sweetness. In some cases, the more bitter the tea, the stronger the lingering sweetness. Polyphenols make these two distinct taste experiences coexist and are closely related.

4%

Amino Acids

Amino acids, which make up about 1-4% of the total content, are primarily responsible for the fresh and refreshing taste of tea. The amino acid content in spring tea is higher than in other seasons, so the fresh taste and lingering sweetness are more pronounced and last longer when tasting spring tea.

4%

Flavonoids

The lingering sweetness effects of flavonoids are not primarily observed in tea, but they have been confirmed as the source of the bitter and sweet flavors in olives. The taste of flavonoids is very unique, presenting a bitter and astringent taste upon entry, but after a period of time, it becomes naturally sweet. In olives, the higher the flavonoid content, the more noticeable the lingering sweetness. Flavonoids make up 4% of the total content in tea.

3%

Organic Acids

Organic acids, which are organic compounds with acidic properties, make up approximately 3% of the total content. They include various types such as malic acid, citric acid, linoleic acid, and others. During the tea-making process, the content of organic acids increases. They stimulate the secretion of saliva, producing a sensation of lingering sweetness and salivation when Drinking Tea.

3.5%

Sugars

In green tea, polysaccharides account for 3.5% of the total content. Although they are named sugars, they are not sweet. Instead, due to their certain viscosity, they remain in the mouth. Through the action of salivary amylase, they are catalyzed into maltose. It is the time lag caused by the catalytic process that creates the effect of bitterness followed by sweetness, known as lingering sweetness.

How to Identify Good Tea Through Lingering Sweetness?

However, the intensity of the sweetness of lingering sweetness is not an absolute basis for distinguishing the quality of tea. For example, some lower-quality teas may have overly bitter and astringent flavors, which produce a stronger sweetness due to the contrast. Also, Black Tea, rich in the sweet-tasting thearubigins, provides more sweetness on the tip of the tongue rather than the lingering sweetness in the throat.

So how can you better judge the quality of the lingering sweetness in a cup of tea? Take a large sip of the tea, allowing it to fill your mouth, and slowly feel its astringency and stimulation. If after swallowing, your tongue surface or underside releases saliva accompanied by a sweet taste that lasts for a long time without diminishing, it can be called persistent