It is widely believed that brewing green tea with boiling water and extending the steeping duration yields the best results. However, a study by Kara et al. (2015) demonstrates the contrary: excessively high temperatures and prolonged brewing times can diminish the beneficial compounds in green tea.
What are the Primary Antioxidants in Green Tea?
Green tea is highly abundant in catechins, particularly epigallocatechin gallate (EGCG), which exhibits potent antioxidant properties and supports cardiovascular as well as metabolic health.
In this study, researchers evaluated the effects of brewing temperature and duration on the total catechin content in green tea.
Results
Brewing tea at 85°C for 3 minutes yielded the highest concentration of EGCG, reaching 50.69 mg/100 mL.
In contrast:
- At 75°C, the EGCG concentration only reached approximately 40.04 mg/100 mL after a 20-minute infusion.
- At 95°C, EGCG levels began to decline after 2–3 minutes due to thermal degradation and conversion into other isomeric forms.
Similarly, the total catechin content peaked at 97.71 mg/100 mL when brewed at 85°C for 3 minutes.
Excessive Water Temperature Diminishes Tea Quality
The researchers observed that when the temperature exceeded 85°C, a fraction of the catechins underwent structural degradation, thereby reducing the concentration of these highly bioactive compounds.
Allowing boiling water to cool for approximately 3–5 minutes prior to brewing can significantly enhance EGCG recovery.
Optimization of Health Benefits and Sensory Profiles
The sensory evaluation panel awarded the highest scores to the tea brewed at 85°C for 3 minutes:
- Color: 8.7/10
- Flavor/Taste: 8.4/10
- Aroma: 8.3/10
- Overall Acceptability: 8.6/10
Conversely, tea subjected to prolonged steeping at high temperatures exhibited increased bitterness, darker coloration, and received substantially lower sensory scores.
Conclusion
To maximize the retention of antioxidants in green tea, the following optimal conditions are recommended:
- Water temperature: Approximately 80–85°C
- Steeping duration: 3–5 minutes
- Boiling water (100°C) is not recommended for immediate brewing.
- Prolonged steeping should be avoided, as it degrades both the sensory attributes and the concentration of beneficial catechins.
Source: Kara et al. (2015). Determination of the optimum brewing conditions for Turkish green tea in terms of catechin content and sensory properties. Journal of Food Science and Technology.