How Matcha Gets its Flavour | The Science of Shading

You might know that some Japanese teas such as matcha and gyokuro are shade-grown, but what exactly does this mean? Today I'll take a look at the history of shade-grown teas, as well as the different types of shading, what types of tea are made in the shade, as well as the science behind how shading affects the flavour of tea. Before I get into that, let's just break down what shading or shade-grown means. In the realm of Japanese tea, shading refers to artificially reducing the amount of sunlight that reaches the tea plants. This differs from natural shading, which can be provided by mountains, fog, or from shade plants, which are tall plants or trees that grow in between the tea bushes and provide shade. When tea, especially Japanese tea, is sold as shaded, it is always artificially shaded. This differs from other products such as coffee, which when they're sold as shade-grown, this means the use of natural shading such as shade plants. While these naturally occurring types of shade produce teas that are noticeably different from those grown in direct sunlight, artificial shading takes this a step further. While it had long been known in China that tea grown on the side of mountains or in shady, foggy valleys produced smoother and mellower tea than bushes grown on sunny flatlands, it was only in Japan that the practice of artificially shading tea plants developed, first as a canopy of straw and bamboo. While we're not sure exactly why these canopies were built in the first place, it is theorized that they were originally used to protect the tea plants from frost damage. The effects of shading were seen as a positive side effect. While we don't know for sure exactly when the first shading canopies were installed, a Portuguese missionary by the name of Joao Rodrigues described them in his book The History of Tea in Japan. He visited Japan in the late 1500s, around 1577, and described the life in Japan that he saw, and he mentioned seeing straw-shaded tea fields in Uji. This celebrated and famous cha then is a small tree, or rather bush. Its new leaves, which are used in the drink, are extremely soft, tender and delicate, and frost may easily make them wither away. So much damage can be done in this way that in the town of Uji, where the best tea is produced, all the plantations and fields from which this cha is grown are covered over with awnings or mats made of rice straw or thatch. They spend a great deal of money on this for the sake of the profit that is to be obtained, as we shall say, for the trade in cha is very great. So we can be sure that sometime in the mid to late 1500s, shading was common enough to be seen in Uji. Interestingly, this is around the exact same time period as the golden age of chanoyu or the Japanese tea ceremony, which means that key players in the tea ceremony history such as Sen no Rikyu and Furuta Oribe would have been drinking bright green frothy matcha, more or less the same as we have today. Before the development of shading, matcha was a sort of pale whitish green and was quite bitter. This major upgrade in the quality of matcha may be a contributing factor in the explosion of Japanese tea culture in the 16 and 1700s. This bamboo and straw canopy style of shading remained more or less unchanged for the next 400 years until the 1960s with the invention of a synthetic fabric that's a sort of black cheesecloth. This replaced the straw in the shading canopies and after this the demand for cheap low quality matcha, which was on the rise, saw the elimination of the canopies altogether and the artificial fabric started being placed on the tea bushes directly. Today this direct style of shading accounts for over 90% of the shaded tea in Japan. Now that you know the history, let's take a closer look at these different shading methods and how they work and the pros and cons of each, starting with the most recent development, direct shading. Direct shading or jikakabuse in Japanese is the cheapest and most common form of shading. This is simply taking a black synthetic fabric and rolling it out across the tea bushes. One layer of this cloth blocks out around 70% of the sunlight and a second layer can be added to block out up to 95%. This style of shading only works on mechanically harvested tea fields as the even surface left by mechanical trimming makes a nice flat surface to put the shading fabric on. The upside to this method is that it's cheap as you don't have to build a canopy and it is more scalable across large machine harvested tea fields. Another upside is that this style of shading is easier to place on hilly terrain where building a canopy is much more difficult. The downside is that laying the fabric directly on top of the tea plants traps in a lot of heat and moisture which lowers the quality of the tea and as I mentioned you have to mechanically harvest the tea plants. As such this is considered the lowest quality of shading though it still produces tasty teas. It is mostly used on senchas and kabusecha along with more affordable matchas and gyokuro. The older canopy style of shading is still preserved and is often called the tana style or shelf style. Most commonly it is used with the same synthetic black fabric as the direct shading. When this fabric is used with a canopy it is called kanreisha. This canopy often made of metal raises the shading fabric above the tea plants allowing for air to flow and the plants to grow much more naturally and breathe more easily. In fact most of the tea plants grown under canopies are grown as shizen shitate. This means natural tailoring and refers to tea plants that are allowed to grow more or less freely looking more bush-like and less like neatly trimmed hedgerows. The natural shape of these bushes produces high quality teas but it also means they are unsuitable for machine harvesting meaning they must be picked by hand. The trade-off for higher quality is of course increased labor and costs. This refers to the hand picking and the building of the canopy so kanreisha is often reserved for higher quality matchas and gyokuro. In fact some of the highest quality award-winning matches and gyokuro use this style of shading but there is one level slightly higher and that is honzu the traditional rice straw and bamboo that has been around for over 400 years. Traditionally logs made of cypress were used to support the canopy but today metal frames are also used. The framework of the canopy is a lattice made of and the first layer of shading is a screen made of reeds and instead of adding an additional layer of reeds the next layer of shading is a sprinkling of rice straw. Again so you can see there's these bamboo reeds and on top of that there's straw so come over here you see the difference where the straw is and then no straw. In comparison to the synthetic fabrics used in the kanreisha style the rice straw bamboo and reeds allow the tea plants to breathe much more easily meaning that the area under the shading is much cooler. You can actually feel the difference from walking from a kanreisha tea field into a honzu shaded tea field it's a night and day difference in temperature and humidity. The downside to this style is that it's much more labor intensive and expensive to build. You have to source rice straw and often the tea farmers would also have a plot of rice next to the tea field so they could use the rice straw for the shading but it's also much more susceptible to fire and that's one reason a lot of people have switched to metal and plastic over wood bamboo and straw. Another minor downside is that the color of tea that is grown under honzu is slightly lighter than that grown under kanreisha even though it's of a higher quality. This means that on the wholesale market where teas are often judged based off of appearance alone the darker more vibrant green of the kanreisha shaded tea leaves looks a little bit more attractive even though the honzu shaded one is of a higher quality. Now you know how tea plants are shaded let's take a look at the types of tea that you can make from these shaded leaves. Because all teas come from the same plant you can technically make any type of tea you want from the tea leaves but for reasons I'll explain shortly only green teas are made from shaded tea plants. Of course matcha is the most famous of these and was the reason that shading was invented in the first place but it is not the only type of shaded tea. While sencha is typically grown in full sunlight some areas such as uji, yame and kagoshima like to shade the tea plants for a little bit usually less than a week just to round off the flavor take away some of the bitterness and increase the umami and the vibrancy of the green color. This okumidori sencha from yoshida meicha en was shaded in the kanreisha style for five days giving it a smooth buttery body and plenty of umami. Shading the tea plants for a little longer usually from one to two weeks produces a tea known as kabusecha which literally translates to covered tea. Kabusechas can vary quite significantly in shading intensity but usually they'll fall somewhere in between a sencha and a gyokuro in terms of taste. This kabusecha hiranami is also from yoshida meicha en but this time it is shaded for 15 days and this one is made from the samidori cultivar. Now that we have a little bit more shading you're beginning to get a distinctive shading aroma known as oika and the reasons for which I'll explore shortly. This is one of my favorite teas from them and it's what I'll be drinking today. Here you can see the 15 days of shading has turned this tea into a beautiful vibrant green. You can see that in the liquor as well. This is a very vibrant bright beautiful green. The shading has given hiranami a really smooth silky texture and lots of umami. It's not quite as intense and in your face as a gyokuro but it's still a lot. Speaking of gyokuro that is the final step in this series of increasingly shaded teas. Teas that are shaded for more than two weeks, usually the rules vary depending where in Japan, are called gyokuro. For a deeper dive into this incredibly luxurious tea see my video on it over here. Today I have quite the rarity. This is a hand-picked gyokuro shaded for 32 days under traditional honzu shading again from yoshida meicha en. I'll drink you in another video. While the length of shading determines the type of tea, when to actually begin the shading is one of the skills of an experienced tea farmer. Shaded tea plants spend most of the year actually unshaded and the 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 has decided it's time to begin shading the first layer is added. This first layer blocks out again around 70% of the sunlight and for shaded sencha sometimes the first layer alone is all that is needed. This will begin to turn the leaf a brighter green and bring out more sweetness and umami. But for the more heavily shaded teas such as kabuseicha, gyokuro and matcha, the second layer is a necessity and it will block the sunlight up to 95%. While 95% shading is enough for most teas you can actually put another layer of shading on top to cut it down to around 99.99%. Doing this almost kills the tea plant but it does produce a very special type of tea that was only recently developed. Hakuyocha, which means white leaf tea, not to be confused with white tea. This is still a green tea but the leaves are white because the tea plant has given up trying to make chlorophyll it's just almost dying the leaves are So maybe we'll see more of this in the future but for now this is a very limited extremely specialty niche product. To understand why we stress tea plants by depriving them of the sunlight they need to survive and thrive we'll need to delve deep into the biology of the tea plant camellia sinensis. And doing that means I'll need another cup of tea. While this subject can be incredibly complicated I've tried to simplify it where I can and focus primarily on the ways that sunlight and shade can affect tea's flavor appearance and aroma. Before we learn how tea reacts to shade we have to first understand how tea interacts with sunlight. So cast your minds back to high school biology because we're talking about photosynthesis. Like all plants camellia sinensis converts light into chemical energy, sugar, through the process of photosynthesis. In simple terms this is the process of using the energy of sunlight to create sugars and starches by combining water from the ground and carbon dioxide from the air with oxygen being produced as a byproduct. This process takes place in specialized cell organelles called chloroplasts which primarily use two types of molecules to collect solar energy. The first type being chlorophylls A and B and the second type being carotenes and carotenoids. Chlorophylls especially chlorophyll A which is the most abundant form in tea plants are responsible for absorbing visible light in the red-orange spectrum and reflecting green light giving tea and most other plants their signature green color. Carotenes and carotenoids such as beta-carotene found in abundance in carrots but also in tea capture blue light and ultraviolet light from the sun transferring this energy to the chlorophylls boosting photosynthesis. When broken down and processing carotenoids produce some of tea's most beautiful and lovely aromas. While tea plants do need sunlight to grow excessive sunlight can actually slow down growth or even damage and kill the tea plants by breaking down chloroplasts and halting photosynthesis. In full sunlight the plants are already receiving too much sunlight for the chloroplast to handle and the plants actually try and reduce the amount of sunlight that they gather by taking their leaves and pushing them up so that there is less surface area being exposed to the sun and additionally they'll convert some of this extra light energy into heat which can be damaging. In addition to carotenoids tea plants also use catechins to capture ultraviolet light from the sun and disperse it as heat. Catechins which are the primary antioxidants found in green tea are mainly used by tea plants as a sort of sunscreen. They will capture the UV in their phenylalanine rings and shoot off the extra energy as heat. Because the tea leaves at the top of the tea plant are closer to the sun these buds and new leaves have the highest concentration of catechins. The catechins found in tea namely epicatechin and epigallocatechin are very powerful antioxidants but in fact they are quite bitter tasting compounds. When tea leaves are oxidized to produce black teas or oolongs these simple catechins link together to form something called polyphenols also known as tannins and this is what gives black teas and oolongs their structure and flavor. Now that you understand what happens to tea in the sunlight let's look at what happens when we get rid of 95% of this light causing the tea to panic. With less sunlight photosynthesis becomes much harder and much less efficient. To compensate for this the tea plant produces much more chloroplasts and chlorophyll up to three times the amount in regular unshaded tea plants. The extra chlorophyll gives the shaded tea leaves their vibrant dark green color. Additionally more carotenes and carotenoids are produced to help capture what little UV light is coming through the shading and convert this extra energy into usable energy for the chloroplast to aid in photosynthesis. Some of the major compounds that come from these carotenoids in shaded green teas are beta-ironone, this is a lovely floral aroma, nerolidol, another floral aroma with a bit more of a green hint to it, safranal which like its name suggests is a mild saffron aroma, and beta-damascenone. I don't know if I'm pronouncing that right. This is how you spell it. This is a sweet almost rosy or fruity aroma. Together these aromatic compounds create the famous and signature shaded aroma or oika of matcha and gyokuro and kabusecha. As the chloroplasts run low on the sugar they need for energy they begin to break down the cell proteins into their component amino acids. Among these is L-theanine. Together with the other amino acids these are responsible for the sweet and savory and umami flavors of tea and as there are more of them in shaded teas naturally shaded teas have more umami and more sweetness. Another amino acid that is produced is methionine which turns into dimethyl sulfide in processing and it is this compound that is responsible for that marine or seaweedy aroma that some teas have. The catechins that I mentioned earlier which act as a sort of UV sunscreen for the tea plant are no longer needed because there is no longer any sunlight to protect the plant from. So instead the plant breaks these down into their component amino acids such as phenylalanine. This is another compound that gets assembled with other things in processing to produce some unique aromatic compounds such as benzaldehyde which is a sort of almondy aroma, benzyl alcohol which is a rosy stone fruit aroma, and 2-phenylethanol which when combined with the beta dimethanone, the one I can't pronounce from earlier, produces a sort of honey aroma. These compounds together with the earlier compounds create an even more unique aroma. Additionally the lack of catechins, a bitter tasting compound, makes the tea less bitter but this is the reason that you can't make good black tea from shaded tea plants because it is these catechins that give black teas and oolong teas their color and flavor and structure. Without the catechins these would be pretty bad teas so shaded tea plants are really only used to make green teas. In short shading increases the sweet and savory tasting amino acids while decreasing the bitter tasting catechins. Wow that's so much simpler when you put it that way. I'm sorry for putting you through the chemistry section but I hope you learned something. If you did learn something about shading or science or bamboo and straw let me know in the comments down below and if you enjoyed this video leave a like. If you want to see more videos like this in the future maybe with a little less science or maybe with more science depending on if you like that section or not hit the subscribe button. Thank you very much for watching and have a nice day!