Why is Japanese Green Tea Shaded?
One of the things that makes Japanese green teas unique is that they are often shaded prior to the harvest. When the tea plant is cut off from the sunlight, it really changes the composition of the leaf, creating a completely different tasting experience.
First, let’s learn a bit about the history of shading. In the 15th and 16th century, tea cultivation was still relatively new in Japan. The climate of the main Island was a bit cold for the tea plant. A lot of farmers began to cover the tea plant during the winter and springtime in order to protect the sprouts of the tea plant from the frost. What they found was this actually yielded a smoother and sweeter flavor. Some farmers began adopting this method, not only to protect their tea plants, but also to improve their flavor. We now know that the reason the shaded tea leaves take on a different flavor is that they produce less catechins and more theanine. When the tea leaf is exposed to sunlight, it begins converting the sweet theanine into more bitter catechins. The plant also produces more chlorophyll, which alters the color of the leaf.
When we visited a farmer on the island of Yakushima, we got to see shaded tea leaves producing more chlorophyll in real time. There was a small hole in the Kabuse netting that let light through on some of the tea plants. As you can see, the plants that were exposed to sunlight are much lighter in color compared to those that were not.
Not all teas are shaded for the same length of time. Many sencha teas are shaded for only about 1 week prior to the harvest, which is enough to reduce a significant amount of their bitterness. The two most prized types of teas produced in Japan are matcha and Gyokuro and those are shaded for the longest time. To be considered a Gyokuro or a true high quality matcha, the tea plant needs to be shaded for at least 3 weeks prior to the harvest.
Oftentimes a farmer will shade a Gyokuro in stages. First they may begin by filtering 50% of the sunlight with one layer of Kabuse netting. After about a week of this, the farmer may add another layer to cut off 75% of the total sunlight. Finally, for the last week or so leading up to the harvest, the farming will add a final layer on top of the tea plant to filter out 90% of the sunlight. This intensive shading accelerates the change within the tea leaves, and produces the unique savory and sweet flavor that Gyokuro is known for.
It’s very difficult to keep a tea plant shaded for 3 weeks or more. Even though the shading process can improve the flavor of the tea greatly, it is a stressful time for the plant. The tea plant produces more caffeine to protect itself from insects, which is why long shaded teas like Gyokuro and matcha are the highest in caffeine.
After the tea plants have been shaded for 3 weeks, they can be harvested. Some Gyokuro is hand harvested so instead of having a simple netting over the plant, the farmers will build a scaffolding. This allows enough space for people to come in and pick the tea. All these people gather together underneath the shade to pick tea for one day out of the year.
When it comes to picking premium teas, you want to go for the top 3 sprouts of the tea plant. These will be the sweetest in flavor and the highest in nutrients. More expensive teas like Gyokuro and sencha will be made from these leaves, while less expensive teas like Bancha will be made from either more mature leaves or later harvests. By using only the top leaves, a farmer is able to create a tea that has an even smoother and sweeter flavor.
Shaded teas tend to contain more caffeine, more theanine and more chlorophyll than their unshaded counterparts. If you are looking for a smoother and sweeter tea, you will want to go for a nice shaded tea like Gyokuro, Kabusecha as well as some shaded sencha teas. Because they have more caffeine and theanine, these teas will also tend to produce more of a calm alert feeling which can be great for long periods of work or study.