· By Team Umi
The Art of Shading: The History & Science Behind How Matcha Develops its Flavour
Table of Contents:
- What is Artificial Shading?
- Brief History of Shading in Japan
- Forms and Styles of Shading
- Types of teas that are produced from shaded leaves
- When does shading begin for Matcha?
- The Science behind how shading affects the flavours of tea
- Why are only Green Teas shaded?
Ever wondered why matcha is shaded, and how this step influences so much of what makes it unique, especially its flavour? Let’s find out.
Green Teas like Matcha, Gyokuro and Kabusecha are shaded or shade grown. It is a well-known fact in China that teas grown in mountains and foggy areas tend to produce better teas (smoother and mellower) when compared to bushes grown on flat land under direct sunlight. While naturally shaded teas produce better quality teas than the one's grown on flat land under direct sunlight, artificial shading takes it a step further.
What is Artificial Shading?
Artificial Shading refers to artificially reducing the amount of sunlight that reaches the tea. This differs from natural shading that is provided by mountains, fog or trees that grow in between tea plantations.
Shade-grown cultivation or hifuku saibai (被覆栽培) is a traditional method in which tea plants are covered for a period of time before harvest, limiting the amount of sunlight that reaches the developing leaves. This deliberate reduction in light alters the plant’s growth and chemical composition, influencing the character of the finished tea.
Also known within the Japanese tea industry as kabuse (被せ), the practice encourages the leaves to develop a deeper green colour, a softer and more delicate texture, and a richer umami character, while reducing bitterness and astringency. These changes contribute to the distinctive flavour and quality associated with shade-grown Japanese teas.
Brief History of Shading in Japan
It was only in Japan that they developed artificial shading in the 1700's using a canopy of straw and bamboo. The exact reason for why they were first developed is not known but it is theorised that these canopies were installed to protect the tea plants from frost damage.
The effects of shading were seen as a result of these canopies, which were first seen in the Uji region, somewhere in the mid to late 1700's. Before the development of shading, matcha was described to be pale white in colour and extremely bitter in taste.
This bamboo and straw style of shading remained the same for more or less the next 400 years until the 1960's with the invention of a synthetic fabric which looked like a black cheese cloth.
A black synthetic fabric was introduced, it was put directly onto the tea bushes and covered, which was known as Direct Shading. After this, the demand for low quality matcha which was already highly in demand saw a rise and lead to the elimination of the elevated canopies altogether.
This direct style of shading accounts for almost 90% of shaded tea in Japan.
Types of Shading:
Direct Shading or Jikakabuse
This style of shading is the cheapest and most common form of shading. A black synthetic fabric is directly rolled on top of the tea bushes. The first layer of fabric provides upto 70% shade and protection and the additional second layer provides upto 95% shade. This type of shading can only work on mechanically harvested tea fields as this leaves an even surface to put the shading fabric on.
Pros: Cheap, scalable across large machine harvested tea fields, easier to place on hilly terrains where building a canopy is difficult.
Cons: Placing the fabric directly onto the tea bushes traps in a lot of heat and moisture which lowers the quality of tea. Hence, this style of shading is mostly used in Sencha, Kabusecha along with most affordable Matcha and Gyokuro.
Tana Shading or Kanreisha
This style of shading resembles the older forms of shading with canopies but instead a black synthetic fabric is used and is elevated with the help of a metal canopy. Most of the tea plants grown under this style of shading are grown as Shizen-Shitate meaning natural tailoring. They are grown naturally and more freely resulting in the tea plants resembling more bush like than neatly trimmed head rows.
The natural shape of these bushes produces higher quality teas but it also means that they cannot be machine harvested and must be handpicked. The trade off for higher quality is the increased labour and costs. This refers to handpicking and building the canopy. Hence, Kanreisha is often reserved for higher quality matcha and gyokuro. Most of the award-winning matcha and gyokuro use this style of shading.
Pros: This allows more airflow to the tea plants and lets them grow much more naturally and breathe more easily as they grow.
Cons: Labour intensive and expensive.
Honzu or Traditional Rice straw & Bamboo shading
This is the highest form of shading. Traditionally, logs made out of cypress were used to make the canopy but today metal frames are also used. The framework of the canopy is lattice made of bamboo and the first layer of shading is a screen made of reeds. The next layer of shading is a sprinkling of rice straw.
Pros: In comparison to the synthetic fabrics used in the Kanreisha or Tana style of shading, the rice straw and bamboo reeds allow the tea plants to breathe much more easily. This makes the area under the shading significantly cooler. You can actually feel the night and day difference in temperature and humidity from walking under a Kanreisha tea field to a Honzu shaded tea field.
Cons: The downside to this style is that it is much more labour intensive and expensive to build. Tea farmers need to source rice straw and often you will see tea fields having a plot of rice farm next to the tea field. It is also much more susceptible to catch fire and that is one of the main reasons for a lot of tea fields switching to metal and plastic rods over wood, bamboo and straw.
Another minor downside is that the colour of the tea that is grown under Honzu is slightly lighter than tea grown under Kanreisha even though Honzu is of a higher quality. This is considered a minor con on the wholesale market where the teas are often judged based off of their appearance alone. The darker, more greener shade of Kanreisha tea leaves looks a little more attractive, even though the Honzu one is of higher quality.
Types of Teas that are produced from shaded leaves
Since all teas come from the same plant: Camellia Sinensis, you can technically make all teas from shaded tea plants but only green teas are made from shaded tea plants. Along with matcha, sencha from the areas of Uji, Yame and Kagoshima like to shade the tea plants for a little while, usually less than a week just to round off the flavour, reduce bitterness, increase umami and the vibrant green colour.
The length of shading determines the type of tea that is derived.
- Sencha: Shaded for less than one week (1-7 days)
- Kabusecha: Shaded for 1-2 weeks (7-14 days)
- Matcha: Shaded for 2-4 weeks (20-30 days)
- Gyokuro: Shaded for 3-4 weeks (30-40 days)
Shading the tea plants for a little longer, usually from 1-2 weeks produces a tea known as Kabusecha which literally translated to covered tea. Kabusecha can vary with taste significantly with shading intensity but they usually fall somewhere between Sencha and Gyokuro in terms of taste. Matcha is shaded for somewhere between 20-30 days depending on the style of shading, farming method and traditions. Gyokuro is the final step of shading in green teas. Teas that are usually shaded for more than 3 weeks (30-40 days) are known as Gyokuro.
When does shading begin for Matcha?
Tea plants are not always shaded. Shading only begins somewhere in the beginning of spring, usually between the emergence of the first new bud and the full growth of the first new leaf. Once the farmer decides it's time to begin shading, the first layer of shading is added. This layer alone blocks out 70% of light.
However, for shaded Sencha, sometimes, the first layer alone is enough. This will begin to turn and bring out more green, sweetness and umami. But for more heavily shaded green teas such as Kabusecha, Matcha and Gyokuro, the second layer is a necessity and will block sunlight upto 95%
The Science behind how shading affects the flavours of tea
To understand what happens to a tea plant when it is grown under heavy shade, we first need to understand what sunlight does to the plant in the first place.
Like other green plants, Camellia sinensis uses photosynthesis to convert light energy into chemical energy. In simple terms, the plant captures energy from sunlight and uses it to transform water absorbed through its roots and carbon dioxide from the atmosphere into the sugars it needs for growth and energy. Oxygen is released as a byproduct of this process.
Photosynthesis takes place within specialised structures inside plant cells called chloroplasts. These chloroplasts contain several pigments that interact with incoming light, with two important groups being chlorophylls and carotenoids.
The chlorophyll family includes chlorophyll a and chlorophyll b. Chlorophyll a is the primary photosynthetic pigment in tea leaves and plays a central role in capturing light energy. It absorbs particular wavelengths of visible light, especially in the blue and red regions, while reflecting more green light. That reflected light is what gives healthy tea leaves their characteristic green appearance.
Tea leaves also contain carotenes and carotenoids, which are collectively known as accessory pigments. One familiar example is β-carotene, the same pigment associated with the orange colour of carrots, although it is naturally present in much smaller amounts in tea leaves. These pigments broaden the range of light that the plant can make use of and also help protect the photosynthetic system when the plant is exposed to excess light. Their role doesn't end with the living leaf, either. During tea processing, carotenoids can break down into smaller volatile compounds, some of which contribute to the complex aromas we associate with tea.
This is where sunlight becomes particularly interesting for tea. The amount and intensity of light available to the plant can influence how it regulates its pigments, photosynthetic activity and the compounds it produces. And when that light is deliberately reduced through shading, as it is in the cultivation of matcha, the plant has to adapt.
That adaptation is the starting point for understanding why shaded tea develops differently from tea grown in full sunlight.
With less sunlight, photosynthesis becomes much harder and less efficient. To compensate for this, the tea plant produces much more chloroplasts and chlorophyll upto three times the amount in regular unshaded tea plants. The extra chlorophyll gives the shaded tea leaves their vibrant dark green colour.
More carotenes and carotenoids are produced as a result, to help capture what little UV light is coming through the shading and convert this extra energy into usable energy for chloroplasts to aid in photosynthesis. Some of the major compounds that come from these carotenoids in shaded green teas are β-ionone which gives shaded green tea its floral aroma.
As the chloroplasts run low on the sugar that they need for energy, they begin to break down the cell proteins into their component amino acids. Among these amino acids is L-Theanine. L-Theanine along with other amino acids are responsible for the sweet, savoury and umami flavours of tea. Hence, sweetness and umami is more naturally found in shaded teas.
Another amino acid that is produced is methionine which turns to dimethyl sulphide in processing and this compound is responsible for the marine or seaweed or nori like aroma that some teas like matcha have. The catechins' that act as a UV sunscreen for the tea plants are no longer needed because there is no longer any sunlight to protect the plant. Thus, instead the plant breaks these down into their component amino acids such as phenylalanine which then is used to produce various other aromatic compounds that also contribute to the unique ‘shaded aroma’ or ooika (覆い香) of shaded green teas.
Some carotenoid derivatives in green teas are:
- Nerolidol: Fresh, green aroma
- Safranal: A saffron aroma
- β-ionone: Floral aroma that can be detected by only about 50% of people
- β-damascenone: A sweet rosy/fruity aroma.
Why are only Green Teas shaded?
Black tea is not shade-grown because full sunlight is required to build the specific chemical compounds needed for its bold, brisk flavour. The lower catechin content in shaded tea leaves is one reason shading is not typically used to produce black or oolong teas. Since catechins are essential for the formation of polyphenols and tannins, their reduced presence would prevent these teas from developing the characteristics associated with these styles. These teas rely on heavy oxidation and processing to develop their rich, malty, or floral profiles. The briskness and robust tannins created by full sunlight are actually desirable traits for these categories, not flaws to be shaded away.
Thus, shading is primarily used in select Japanese green teas, including matcha, gyokuro, and kabusecha. By limiting the plant’s exposure to sunlight before harvest, growers encourage the development and retention of the naturally sweet, umami-rich, savoury and delicate flavours and also to reduce its bitterness. These are characteristics that are prized in these teas and are not usually preferred in black and oolong teas.