Two Types of Tea Firms

For Japanese tea, there are two types of cultivation.

One is "open air cultivation" for Sencha (i.e. grown under the full sun), and the other is "under-shaded cultivation" for Gyokuro and Tencha (material of Matcha) .

Due to the sunlight, amino acid (the source of umami) in tea leaves changes into catechin (the source of astringency). Therefore, Sencha grown under the full sun has pleasant astringency.

On the other hand, Tencha  and Gyokuro tea leaves are shielded from the sun about for 20 days or more after new buds come out. This causes the amino acids known as theanine in the tea leaves to remain instead of changing into catechin. This shading process gives the special flavor and aroma to Tencha and Gyokuro.
The other day, I was fortunate to visit Gyokuro tea firm in Kyoto. My hands-on experience for picking-Gyokuro tea story is coming soon.

Under-shaded tea firm (called "Ooishita-en")

Open-air tea firm (called "Roten-en")