Camellia taliensis: is caffeine-free tea a myth?

6 mai

Have you ever seen serrated tea leaves? Scaly buds? In recent years, more and more tea stores have been offering teas made from Camellia taliensis, a species of tea plant commonly found in the wild. Some sellers describe these teas as low in caffeine. Yet it's a cousin of the famous camellia sinensis assamica, the most widely used tea plant, and it's well known that the vast majority of tea leaves are rich in caffeine.

This issue was already topical in the 2000s. In 2008, Gao et al. investigated the caffeine composition of green tea leaves from cultivated Camellia sinensis var. Assamica (a caffeine-rich tea species) and wild Camellia taliensis. The authors showed that both batches of tea leaves contained caffeine (2.32 and 2.94% caffeine) at levels close to those reported in tea research (2% to 3% on average).

More recently, Zhang et al. studied the genetic signature of Camellia Taliensis with Camellia Sinensis, which enables the synthesis of caffeine. The plant transforms a molecule called xanthosine into various products such as theobromine, until it arrives at the final molecule: caffeine.

The plant's genetic code dictates its ability to produce these transformations. The genetic signature of Camellia Taliensis for caffeine synthesis is thought to be close to that of Camellia Sinensis, and may even be more pronounced in certain parts of the plant, such as flowers and buds. This may be explained by the fact that caffeine is a chemical defense molecule against pests. As Camellia Taliensis is a wild species, it must be able to protect itself by producing defense molecules.

So if Camellia Taliensis contains caffeine like its cousin, why do some sellers sell it as a “low-caffeine” tea?

Just as there are wide variations between Camellia Sinensis in terms of caffeine, the same is true for Camellia Taliensis. Ogino et al., specialists in the study of tea plants, were interested in Japanese Camellia Taliensis, which contained more theobromine (precursor of caffeine) than caffeine. After establishing crosses between tea plants resulting in a hybrid tea plant called Taliensis-akame, the authors showed that this Camellia Taliensis possesses a marker (“CafLess TCS1”) in one of the caffeine synthesis genes. This marker prevents expression of the gene, so that tea leaves no longer synthesize caffeine correctly.

Beware: tea buds and leaves from Camellia Taliensis may contain as much caffeine as other tea leaves. To indicate that these teas contain less caffeine, a chemical analysis of the leaves is required. Indeed, some Camellia Taliensis may produce less caffeine, depending on their initial genetic status and how the tea plants have reproduced (in contact with other, less caffeinated tea plants, etc.).