We all know that you can enjoy your tea that you have just brewed for 30 seconds as the same as a forgotten mug of tea that’s been steeping for 30 minutes, drinkable shouldn’t be your goal.
[Tweet “The taste will a depends on the type of tea you’re drinking”] But the antioxidant and caffeine levels all depend on the amount of time the leaves are in contact with the water. So how early is too early to pluck out a tea bag, and how long can you leave it in before passing the point of no return?
[Tweet “THE SCIENCE OF STEEPING TEA”]
To successfully get the perfect timing, you first need to understand the chemical process at work when you pour hot water over tea leaves. Black, green, white, and oolong tea all come from the leaves and buds of the same plant, Camellia sinensis. (Herbal teas aren’t considered “true teas” because they don’t come from C. sinensis.)
Heat is being introduced to green and white tea leaves to dry them, limiting the amount of oxidation they get, while black and oolong tea leaves are exposed to oxygen before they’re dried, creating the chemical reactions that give the tea its distinct color and flavor. Damaging the tea leaves—by macerating them, rolling them gently, or something in between—helps expose the chemicals inside their cells to varying levels of oxygen.
Green and black teas contain a lot of the same chemical compounds that contribute to their flavor profiles and nutritional content. When the leaves are submerged in hot water, these compounds leach into the liquid through a process called osmotic diffusion, which occurs when there’s fluid on both sides of a selectively permeable membrane—in this case, the tea leaf. Compounds on the surface of the leaf and in the interior cells damaged by processing will diffuse into the surrounding liquid until the compounds in both the leaf and the water reach equilibrium. In other words, if given enough time to steep, the liquid in your mug will become just as concentrated with tea compounds as the liquid in your tea leaves, and the ratio will stay that way.
Osmotic diffusion doesn’t happen all at once—different compounds enter the water at different rates based on their molecular weight. The light, volatile chemicals that contribute to tea’s aroma and flavor profile dissolve the fastest, which is why the smell from a bag of tea leaves becomes more potent the moment you dunk it in water. The next group of compounds to infuse with the water includes the micronutrients flavanols and polyphenols, which are antioxidants, and caffeine. They’re followed by heavier flavanols and polyphenols such as tannins, which are the compounds responsible for tea’s bitter flavor.