Kukicha (Stem Tea / Twig Tea)

1. What is kukicha?

Kukicha(茎茶) is a by-product in the process of making final sencha, tamaryokucha, or gyokuro tea products.

To make final tea products, crude tea is dried further to reduce moisture.
Then tea stalk separator separates stems and small particle leaves from leaves.  In Japanese, we call them demono(出物).
Examples of demono are kukicha(茎茶), mecha(芽茶), and konacha(粉茶).

For kukicha, In general, karigane(雁が音) and shiraore(白折) are called high-grade stem tea separated from high-grade gyokuro and sencha products.
Meanwhile, we learned at the Japanese Tea Marathon that people call stem tea differently by region.
For example, one Yame farmer calls gyokuro stem tea ‘kukicha’, while one Kagoshima farmer calls high-grade gyokuro stem tea ‘karigane’.

All names below are used to call stem tea (twig tea).

Karigane(雁が音)
Shiraore(白折)
Kukicha(茎茶)
Bō cha(棒茶)

 

2. How is stem different from leaf?

Stems are located between root and leaf.
Theanine, umami component is composed in root and delivered to leaf.
Once the theanine is carried to the leaf, sunlight decomposes theanine into ethylamine and glutamic acid.
Ethylamine is decomposed into other chemical components and used to create catechins.

Theanine is converted to catechin on leaf with sunshine

The stem is less exposed to sunlight and preserves theanine and creates fewer catechines than the leaf.

The following picture is the comparison of chemical components(content %) by leaf position and stem.
1 tip 2 leaves(一芯二葉) is regarded as high-quality Japanese tea material.

Chemical Components by Leaf Position and Stem - 1st Harvest

The stem has more than 2 times theanine component than the highest quality 1 tip 1 leaf.
Stem tea has more umami than leaf tea!
And it has less than half of caffeine and catechines as 1 tip 1 leaf.
This means it tastes less bitter and less astringent.
And the liquid color is lighter.

If you like the balance of umami, sweetness, bitterness, and astringency, then leaf teas are recommended.
If you want to fully enjoy the umami taste, kukicha is a good option to try.

3. Aroma of kukicha

If you have already tried stem tea, you have probably noticed that it not only tastes but also smells different from leaf tea.

It is assumed that the lighter taste of stem tea is probably due to the fact that it contains less catechins and caffeine than the leaf tea.

Stem tea has a distinctive stem or wood-stem scent.
We will introduce some major difference of the aroma compounds contained in the leaf tea and stem tea.

Aroma Components More in Stem Tea than in Leaf Tea

Interestingly, cis-3-hexen-1-ol, the aromatic component of fresh green leaves, was abundant in the stem tea.
It is curious why cis-3-hexen-1-ol is rich in the stems, since green photosynthesis is often carried out in the leaves.

Also, linalool, which has a scent similar to lily of the valley, lavender, or bergamot, is more than twice as abundant in the stem tea.
Geraniol, which smells like roses, is three times more abundant in the stem tea.

Could you detect these aromas in your stem teas?

Aroma Components More in Leaf Tea than in Stem Tea

This research paper compared the major 21 aroma compounds in stem tea and leaf tea.
Out of the 21, only 5 have more in stem tea than in leaf tea.
This implies that stem tea is simpler than leaf tea not only in taste but also in aroma.
The table above shows the list of aroma components that are about twice as much in leaf tea than stem tea.

Stem tea does indeed have a distinctive stem smell,
but the woody-smelling cedrol that was speculated to be the source was found less in stem tea than in leaf tea.

It is assumed that the scent of lily of the valley with linalool and rose with geraniol created the special scent of the stem,
but how the floral fragrances relate to the stem aroma is still a mystery.

Check Kukicha products