In order for the fermentation process to take place, the yeast in a SCOBY needs things to feed on, which is why you add sugar during the brewing process, per tea manufacturer Teatulia. It also needs nutrients from the tea leaves, specifically nitrogen, theanine, and caffeine. These nutrients are generally scarce in herbal teas, but they are abundant in so-called “true tea.” Another tea manufacturer, Rishi, explains that “true tea” refers to the leaves of the Camellia sinensis plant. From this single bush, we get black, green, white, yellow, oolong, and Pu’er teas, all differentiated by how the leaves are oxidized.
According to Teatulia, you should use either black, green, or oolong tea to give yourself the best shot at a successful batch of home-brewed kombucha. You can even blend all three. Avoid tea blends that contain chamomile or peppermint, as both contain natural oils that can harm the SCOBY. For this same reason, you want to avoid any teas that contain oil for flavoring. With a little know-how, you can avoid this common pitfall in kombucha brewing.