In a decoctive episode of the BBC series Inside The Factory, host Cherry Healey consults food scientist Dr. Stuart Farrimond to learn how to prepare a proper cuppa when using a tea bag. He advises her to first ditch the styrofoam cup and replace it with a red mug, as the color red psychologically makes food taste taste sweeter. He then filters the water before boiling in order to remove the hardening minerals. Once boiled, he pours the water over the bag steeps for five long minutes. The steep time raises caffeine and antioxidant to fully release within the brew.
It is a long time but it’s gonna be too hot to drink anyway, so you’ve got to leave it. There’s more (of) the flavor coming out and also the more caffeine comes out, the stronger the tea will be. There’s also more (of) the antioxidants coming out. Tea is a great source of antioxidants and these are natural substances that our body uses to help fight disease. So it is important that you leave it to brew.