Tea Stalks – Theanine – Happiness
Tea stalks are often overlooked, playing the role of sidekick to the tea leaves they support. But did you know that tea stalks contribute significantly to tea’s health benefits? In particular, tea stalks are abundant in the amino acid theanine. And much more so than the leaves!
But first, what is theanine? Theanine (the form commonly referred to is L-theanine) is an amino acid found in tea plants. It accounts for about 50% of all the amino acids found in tea leaves (including the stalks). It also contributes to the “umami” or savory flavor in tea. Theanine has a sedative effect because it promotes the release of dopamine from the brain and the generation of alpha brain waves. Because theanine creates a relaxed and comfortable feeling in the body, it is sometimes called the “happiness amino acid.”
To understand how theanine is distributed, Taiwan’s tea research agency designed a study where the plucks contained a bud and six leaves. The illustration below shows the position of leaves and stalks.
The various sections were freeze-dried and ground, then solids were extracted by steeping in 90oC hot water for 20 minutes. The data showed:
- For leaves, the amount of theanine was:
- Highest in the bud-and-first-leaf (12.46 mg/g)
- Lowest in the sixth leaf (1.98 mg/g).
- For stalks, the amount of theanine was:
- Highest in the second stalk (67.16 mg/g)
- Second highest in the first stalk (62.18 mg/g)
- Lowest in the fifth stalk (20.29 mg/g).
These results showed that tea stalks possessed way higher amounts of theanine compared to leaves. Compared to bud-and-first-leaf, theanine level for first and second stalks were more than 5 times higher. Even fourth and fifth stalks had about twice the theanine amount. These results were consistent with those derived from a previous study.1
Furthermore, tea stalks contain much less caffeine than leaves. Based on the same study, the amount of caffeine was:
- For leaves: highest in the first leaf (54.42 mg/g); the amount in the second to the sixth leaf was around 40 mg/g
- For stalks: highest in the first stalk (22.44 mg/g); about 9.72 mg/g in the second stalk; the amount decreases proportionally in the lower stalks.
The first stalk contained about 50% of the caffeine amount in leaves; the second stalk about 25%. Overall, one can conclude that stalks contain only about 10~50% of the caffeine found in leaves.
Who knew that tea stalks – sometimes discarded during tea’s post-production refining process – are so abundant in theanine. Or that they play such an important role in promoting the relaxed happy feeling we get from drinking tea. Being low in caffeine, tea made with tea stalks is also an excellent alternative for tea drinkers sensitive to caffeine.
Tea stalk teas are sometimes nicknamed “Happiness Tea.” If you are interested to try some, check out the ”HIGH MOUNTAIN WULONG Happiness Tea” we offer here at Taiwan Tea Connection.
* Source: Extracted from TRES (Taiwan Research and Extension Station) Tea Industry News (2017).
1. A similar study was conducted in 1976 research by Professor Wu Zhenyi and Yeh Suching (Taiwan Research and Extension Station). Results summary: Theanine level of upper stalk is higher than lower stalk (upper stalk: 43.20 mg/g, lower stalk: 38.93 mg/g). The lower stalk has more theanine than the bud-and-first-leaf (8.59 mg/g). The fourth leaf contains the least theanine (6.57 mg/g).