Does boiling water destroy catechins in green tea and ruin its benefits?

December 4, 2025 •

4 min read

According to scientific research, epigallocatechin gallate (EGCG), the primary and most potent catechin in green tea, undergoes degradation and epimerization when subjected to high temperatures for prolonged periods. So, does boiling water destroy catechins in green tea and compromise its health benefits? The answer is nuanced, depending on both temperature and time.

Quick Summary

Boiling water can degrade sensitive catechins in green tea over prolonged steeping, altering the chemical composition and affecting both its health benefits and flavor profile.

Key Points

Boiling water degrades catechins: High temperatures, especially with longer brewing times, cause delicate catechins like EGCG to break down through epimerization.
Optimal temperature is crucial: The ideal brewing temperature for green tea is around 80-85°C (176-185°F) to maximize catechin extraction while minimizing degradation.
High heat creates bitterness: Boiling water extracts excessive tannins, resulting in a harsh, bitter, and astringent flavor profile instead of the tea's natural sweetness.
Timing is key: Steep green tea for 3-5 minutes at the optimal temperature for the best balance of flavor and antioxidant content.
Adding lemon can help: The vitamin C in lemon juice can significantly boost the bioavailability of green tea catechins, helping your body absorb them more effectively.
Use loose leaf for re-steeping: High-quality loose-leaf green tea retains more catechins for potential re-steeping compared to processed tea bags, though the first brew is always the most potent.

The Science Behind Green Tea Catechins and Heat

Green tea is celebrated for its high concentration of polyphenols, specifically catechins, which are potent antioxidants. The most well-known and researched catechin is epigallocatechin gallate, or EGCG. These compounds provide green tea with its numerous health benefits, including supporting cardiovascular and cognitive health. However, catechins are sensitive to heat. When exposed to high temperatures, particularly for extended periods, they can undergo a process called epimerization, which converts them into less active forms. This chemical alteration means that while boiling water is effective at extracting compounds from the tea leaves, it can also lead to the breakdown of the very antioxidants people seek. Studies have identified specific temperature points where these reactions accelerate significantly.

Brewing Temperature vs. Catechin Extraction

Hot water plays a dual role in brewing green tea. On one hand, higher temperatures increase the rate at which soluble compounds, including catechins, are extracted from the tea leaves. The heat helps break down the plant's cell walls, allowing for a more efficient transfer of catechins into the water. On the other hand, excessively high temperatures, especially for longer durations, promote the degradation and epimerization of the most fragile catechins, like EGCG. This means that while you might initially pull more catechins out with boiling water, you risk destroying some of them in the process. The goal is to find the perfect temperature and time balance that maximizes extraction while minimizing degradation.

Finding the Optimal Brewing Method

Numerous studies have investigated the ideal brewing parameters to maximize catechin content and antioxidant capacity. An optimal brewing window often cited is between 80-85°C (176-185°F) for approximately 3 minutes.

Tips for optimal green tea brewing:

Use the right temperature: Heat your water to between 80-85°C. If you don't have a variable-temperature kettle, bring the water to a boil and let it cool for 3-5 minutes before pouring.
Steep for the correct duration: A steeping time of 3-5 minutes is generally recommended. This allows for sufficient extraction without causing excessive bitterness from degraded catechins.
Use quality leaves: Higher quality, loose-leaf green tea often yields better results in terms of both flavor and antioxidant levels.
Consider a vitamin C boost: Adding a splash of lemon juice has been shown to enhance the bioavailability of catechins, helping your body absorb more of the antioxidants.

The Impact on Flavor

High temperatures do more than just affect catechin stability; they also significantly impact the flavor profile of green tea. When leaves are steeped in boiling water, the heat rapidly extracts not only the desirable compounds but also excessive amounts of tannins. This is what creates the harsh, bitter, and astringent taste often associated with improperly brewed green tea. Brewing with cooler water, on the other hand, extracts more of the delicate, sweeter amino acids, like L-theanine, resulting in a smoother, less bitter, and more nuanced flavor. This is why traditional Japanese green teas, such as Gyokuro, are often brewed at much lower temperatures.

How Other Factors Influence Catechin Content

Brewing parameters are not the only things that affect the final catechin levels in your cup. Other factors include the type of tea, leaf size, and water quality. The storage of the tea leaves is also crucial, as catechins can degrade over time, especially when exposed to heat and light. Using fresh, well-stored tea leaves is important for ensuring the highest antioxidant content.

Comparison of Brewing Methods


Feature	Boiling Water (100°C)	Optimal Water (80-85°C)
Catechin Levels	High initial extraction, followed by rapid degradation and epimerization.	Efficient extraction with minimal degradation, maximizing beneficial compounds.
Flavor Profile	Prone to bitterness and astringency due to high tannin extraction.	Smoother, sweeter, and more complex flavor, bringing out the tea's natural notes.
EGCG Stability	Significantly reduced due to high temperatures degrading the compound.	High stability, preserving the most potent antioxidant for consumption.
Recommended Use	Avoid for delicate green teas; may be acceptable for robust, lower-grade teas like bancha.	Recommended for most green teas to achieve the best flavor and health benefits.

Conclusion

While boiling water won't instantly obliterate all the catechins in your green tea, it certainly doesn't represent the ideal brewing method for preserving these delicate antioxidants and maximizing health benefits. The high temperatures accelerate both the extraction and the degradation process, leading to a diminished nutritional profile and a noticeably bitter taste. For the best cup of green tea, both in terms of flavor and health-promoting properties, opt for water heated to around 85°C and a steeping time of just a few minutes. Adopting the correct brewing technique is a simple yet powerful way to ensure you are getting the most out of every cup of green tea you drink. For further reading, an in-depth study on the effects of brewing conditions on catechin content is available here: Effects of different brewing conditions on catechin content and sensory characteristics of Turkish green tea.

Common Brewing Mistakes

Over-steeping: Steeping for too long, even at a lower temperature, can increase bitterness and degrade antioxidants. Stick to the recommended 3-5 minutes.
Using low-quality leaves: The starting material matters. Higher quality loose-leaf tea will contain more catechins and better flavor.
Ignoring water quality: Impurities in tap water can affect the taste of your tea. Using filtered water is often recommended.
Adding milk: Dairy can bind to catechins, reducing their bioavailability and limiting the health benefits.
Reusing tea bags too many times: While some loose-leaf teas can be re-steeped, the majority of catechins are extracted during the first brew, and subsequent brews yield significantly fewer beneficial compounds.

Frequently Asked Questions

The ideal temperature for brewing green tea is between 80-85°C (176-185°F). This temperature range effectively extracts catechins and other compounds without causing them to degrade or release too many tannins, which creates a bitter taste.

Yes, hot water does extract more catechins and other antioxidants than cold water. However, the key is the temperature and time. Boiling water can cause catechins to degrade, so brewing at a slightly lower, optimal temperature is best for preserving them.

A steeping time of 3 to 5 minutes is generally recommended for green tea brewed at the optimal temperature of 80-85°C. This period allows for sufficient extraction of beneficial compounds while avoiding excessive bitterness.

It is not recommended to add dairy milk to green tea if you want to maximize its health benefits. Research suggests that proteins in milk can bind to catechins and reduce their bioavailability, inhibiting your body's ability to absorb the antioxidants.

Yes, adding a splash of lemon juice to your green tea can be beneficial. The vitamin C in citrus fruits has been shown to increase the absorption of catechins, enhancing the tea's antioxidant effects.

Brewing green tea with boiling water can scorch the delicate leaves, causing a harsh, bitter taste due to the rapid release of tannins. It also accelerates the degradation of sensitive catechins, potentially reducing the tea's health-promoting properties.

Cold brewing green tea can be an effective way to preserve certain catechins, as the low temperature prevents heat-induced degradation. While the extraction process is much slower, it can yield a brew with a high antioxidant capacity and a smoother, less bitter flavor.