All tea is produced from the leaves of Camellia sinesis plant. The type of tea that is made depends on how those leaves are processed after they are picked. Tea processing is called oxidation or fermentation. There is a really neat picture (via Katherine’s Tea Pot) to the right depicting the 5 main types of tea – left to right there is white, green, oolong, black, Pu-erh tea.
Once the tea leaves are harvested they are intentionally broken or rolled to begin the enzymatic reaction of oxidation. In the process, oxidases being to break down the chlorophyll in the leaves, smaller polyphenols are combined to form larger ones, and the leaves gradually become darker. White teas are tea leaves that have not been fermented at all, while black teas are fully fermented tea leaves, and Pu-erh tea is not only fully fermented but also aged.
During the oxidation process, the major polyphenols that are produced are theaflavins and thearubigins (pu-erh tea also has special polyphenols called theabrownins). These polyphenols are specific to teas and are the compounds that give drinks like black tea its darker, reddish brown color and are also the most notorious tea staining molecules.
Not only do theaflavins and thearubigins produce stains that are more visible than the other tea polyphenols, but they also have a much higher affinity for the protein pellicle of your teeth, which means these stains are more likely to stick to your teeth. Both of these reasons are why more oxidized teas tend cause more staining.
We have already mentioned that looking at the color of your tea is a pretty good way of judging it’s staining capacity because these molecules give oxidized teas their darker and even reddish color, but the bottomline is that you should opt for unfermented white tea or lightly oxidized green teas to reduce staining that can result from drinking tea.