The "Astringency" of Tea: A Unique Tasting Experience

In the world of tea, "astringency" is a frequently mentioned yet often misunderstood concept. Many people simplify it as a specific taste, but in reality, it’s a much more complex sensory experience. This article delves into the nature of astringency in tea, exploring its essence and its important role in tea quality and health benefits.

Introduction: Understanding "Astringency" in Tea

When we taste a cup of tea, our tongues detect a variety of flavors: sweet, sour, bitter, salty, and umami. These are the basic tastes we’re familiar with, perceived by taste buds that send signals to the brain. However, "astringency" is a unique sensation that is different from these basic tastes—it's more of a tactile feeling in the mouth.

Astringency is not just a flavor, but a tactile sensation, a result of physical and chemical reactions in the mouth. 

To truly understand astringency, we must go beyond traditional taste concepts. Astringency is not just a flavor, but a tactile sensation, a result of physical and chemical reactions in the mouth. This feeling might remind us of certain fruits, like unripe persimmons or green grapes, but in tea, it has a more subtle and complex expression.

The Scientific Nature of "Astringency": Sensation vs. Taste

Why is "astringency" considered a sensation rather than a taste? The answer lies in the complexity of our sensory system. The American Society for Testing and Materials (ASTM) defines "astringency" as the puckering or tightening feeling caused by exposure to polyphenolic compounds.

From a physiological perspective, our tongue and mouth are lined with various types of sensory receptors. Taste buds detect basic tastes, while touch receptors sense temperature, texture, and pressure. The sensation of "astringency" is primarily triggered by these touch receptors.

When certain compounds in tea (mainly polyphenols) interact with proteins in the mouth, they cause minor changes on the oral surface. These changes activate the touch receptors, sending signals to the brain, and we perceive the "astringency." This process is distinct from the mechanisms that allow us to perceive sweet, sour, or bitter tastes.

Tea Polyphenols: The Main Source of Astringency in Tea

The "astringency" in tea primarily comes from tea polyphenols, particularly catechins. Catechins are powerful antioxidants, making up 10-15% of the dry weight of tea, and 70-80% of the total polyphenol content. These figures explain why astringency plays such a significant role in the evaluation of tea quality.

The content and type of catechins vary depending on the tea variety, growing environment, and processing methods. For example, the large-leaf tea varieties from Yunnan often have higher catechin levels, which explains why green tea or raw pu-erh made from these leaves tend to be more astringent compared to teas made from smaller-leaf varieties.

It's important to note that during processing and storage, the catechin content in tea changes. The more fermented the tea, the lower its catechin content, and consequently, its astringency. This explains why ripe pu-erh tea is generally milder than raw pu-erh. Similarly, both raw pu-erh and white tea become less astringent over time as they age.

The Experience of Astringency in the Mouth

The astringency in a good tea is often dynamic: it starts with a strong tightening sensation, followed by an increase in saliva production that brings a soothing, moistening feeling. 

How does the feeling of "astringency" develop and evolve in the mouth when drinking tea? This process involves a series of complex physiological reactions.

First, our saliva contains various proteins that serve to moisten, lubricate, and protect the oral mucosa. When the polyphenols in the tea come into contact with these proteins, a chemical reaction occurs, causing the proteins to denature and lose their lubricating properties.

As lubrication decreases, friction in the mouth increases. This friction activates mechanical receptors in the oral cavity, sending signals to the brain, and we perceive the "astringency." This sensation is typically described as a contraction or dryness in the mucous membranes of the mouth.

However, the experience of "astringency" is not limited to this. Tea polyphenols also stimulate the salivary glands, promoting the secretion of saliva. This is what we refer to as the "salivation" effect. Therefore, the astringency in a good tea is often dynamic: it starts with a strong tightening sensation, followed by an increase in saliva production that brings a soothing, moistening feeling. This process is commonly summarized as "bitterness followed by sweetness, astringency followed by salivation."

Astringency and Tea Quality

A high-quality tea should have a balanced and dynamic astringency.

In tea quality evaluation, the expression of "astringency" is a key indicator. However, this does not mean that a stronger astringency indicates higher quality. In fact, a high-quality tea should have a balanced and dynamic astringency.

Good astringency should have the following characteristics:

• Rapid Dissipation: The initial tightening sensation should quickly dissipate and not linger too long on the tongue.
• Clear Salivation: As the astringency evolves, there should be a noticeable increase in saliva secretion.
• Comfortable Mouthfeel: The entire process should feel comfortable, without a prolonged dry or rough feeling in the mouth.

Conversely, if the astringency lingers too long, doesn't transform well, or causes discomfort in the mouth, this typically indicates lower tea quality. This could be due to poorly structured polyphenols in the tea or issues during the tea’s processing.

When tasting tea, we can use the comfort of astringency and the degree of salivation as two important indicators of quality. A good tea should strike a balance between astringency that adds richness to the flavor and smoothness that ensures a pleasant drinking experience.

The Variation of Astringency in Different Types of Tea

Different types of tea exhibit unique astringency characteristics due to variations in raw materials, processing methods, and storage conditions. Understanding these differences helps us better appreciate and choose teas.

• Green Tea: Generally has a more pronounced astringency, especially in teas made from large-leaf varieties. Green tea retains a high level of catechins during processing, making its astringency more intense initially, which gradually weakens over time.
• White Tea: Initially may have noticeable astringency, but as it ages, this turns into a more mellow, sweet taste. This is due to the changes in polyphenols during storage.
• Oolong Tea: With partial fermentation, oolong teas tend to have milder astringency than green tea but stronger than black tea. The degree of fermentation influences the level of astringency in oolong tea.
• Black Tea: As a fully fermented tea, black tea generally has a weaker astringency. The tea liquor usually presents a rich, smooth flavor, with astringency well-integrated into the overall taste.
• Pu-erh Tea: Raw pu-erh tends to be quite astringent in its early stages but becomes less so with aging. Ripe pu-erh, due to its post-fermentation process, generally has a weaker astringency, resulting in a unique, mellow flavor.

Understanding these differences allows us to better anticipate and appreciate the distinct astringency expressions of each type of tea.

Health Benefits Associated with "Astringency"

While astringency may sometimes be perceived negatively, it is closely linked to many of the health benefits of tea. The primary compounds responsible for astringency—catechins—are among the most active and beneficial components of tea.

The health benefits of catechins include:

• Strong Antioxidant Properties: Helping to neutralize free radicals and reduce oxidative stress.
• Anti-inflammatory Effects: Potentially alleviating chronic inflammation.
• Anticancer Potential: Some studies suggest catechins may help prevent certain types of cancer.
• Cardiovascular Health: Potentially reducing the risk of cardiovascular diseases.
• Radiation Protection: Some research shows catechins might have a protective effect against radiation.
• Oral Health: The astringent nature of tea polyphenols can help maintain oral hygiene.

However, it’s important to note that while these health benefits are promising, most research is still in its early stages. We should view tea as part of a healthy lifestyle, rather than a "miracle cure."

Conclusion: Embracing "Astringency" in Tea Appreciation

In the tea drinking process, we should not simply reject or seek out astringency. Instead, we should learn to appreciate its variations and balance. 

From our exploration, it’s clear that "astringency" is much more than a simple taste—it’s a complex sensory experience. It not only reflects the quality and characteristics of tea but is also closely linked to its health benefits.

In the tea drinking process, we should not simply reject or seek out astringency. Instead, we should learn to appreciate its variations and balance. A good tea’s astringency should be dynamic and harmonious, providing rich layers of flavor and a delightful drinking experience.

At the same time, we should recognize that pursuing health benefits does not mean selecting the most astringent tea. Rather, we should choose teas that suit our individual taste preferences and are enjoyable for long-term consumption. After all, the highest realm of tea appreciation is finding joy and balance in the experience.

References:

American Society for Testing and Materials (ASTM): https://www.astm.org/