Tea is well known for its antioxidant properties, but the amount of antioxidants in the tea you get depends on the heat and the type of tea.
A 2015 study published in the Journal of Food Science found that the antioxidant content of tea varies depending on the type of tea used and how hot the water is.
As for green tea, the amount of antioxidants is highest when steeped in cold water for a long time.
Black tea produces the most antioxidants when brewed for a short time in very hot water.
Oolong tea (partially fermented tea) was tested in another 2015 study. Results showed that oolong tea is very sensitive to high temperatures. So, if you want to maximize the antioxidants in oolong tea, you should drink the tea brewed with cold or lukewarm water.
However, if you prefer to drink hot green tea, you can still get antioxidants if brewed at a specific hot temperature. One Turkish green tea study tested brewing green tea at 75, 85, and 95 degrees. As a result, brewing green tea at 85 degrees for three minutes showed the highest levels of antioxidants.