Researchers, however, have found that using boiling water and longer steeping times increases the amount of polyphenols in the green tea. Polyphenols are the antioxidants in green tea that are responsible for the health benefits that green tea is believed to have.
The results of the studies done suggest that the following preparation guidelines can boost the polyphenol level in green tea:
Size of tea leaves - Small loose leaf green tea is the best choice, because it infuses quickly. Tightly curled or large leaf tea requires a longer infusion time.
Loose leaf vs. teabags - Loose leaves are preferable to teabags. In order to increase the extraction of polyphenols, teabags should be continuously dunked in the teapot rather than left to float on the water.
Temperature - Boiling water promotes the extraction of polyphenols.
Steeping Time - Tea should be steeped for two to five minutes. The polyphenol content of tea increases with steeping time, while a shorter steeping time results in a high caffeine content but low polyphenol content.