Pu’er, or dark tea is the only tea that contains probiotics, or “good” microbes. It can be aged for many years, and increases in value accordingly.
This tea is commonly available in cake or brick form, but is also available as loose leaves, sometimes aged in bamboo. It is important not to break the leaves when prying them from the cake, as this will damage them, making the tea bitter.
Pu’er continues to ripen and age over time, so can be kept for many years and tasted each year to experience the developing flavours.