Different teas require different brewing temperatures to bring out their best qualities. Lighter teas such as green and white teas can taste bitter or sharp if brewed too hot. This is because the heat scalds the leaves so they release astringent tannins – it also destroys some of their complex aroma compounds. So wait two to three minutes before infusing a white or green tea. For darjeeling and oolong teas wait just a few moments after boiling the kettle. And for all other black and rooibos teas you can brew straight away once the kettle has boiled.