CULTIVATION OF GREEN TEA FROM PLANTING TO THE FINAL PRODUCT
In order to achieve favorable harvesting conditions, the tree is kept small, they are cultivated like shrubs. that means the tea tree usually reaches a height of about 1-2 meters. However, it should be noted that under the right circumstances the tea tree can reach a height of up to 15 meters at high altitudes, in well drained soils.
But because of the looks of the plant, most people speak of a bush but in fact, it’s a tree.
Nowadays two methods are used to cultivate plants. According to the less common method, the traditional one, the seeds are pre-germinated under moist jute fabric and then allowed to grow. Today the vegetative method, with which seedlings are grown, is used almost exclusively. This allows a constant plant quality, because the plant could adapt to the environmental conditions over centuries.
The life of every tea tree starts as a seedling. Spring around March, April is the common planting time for seedlings. After around 4 years the tree is ready for the first harvest. But only after around 5 to 8 years, the leaves and buds are enriched and the harvest and quality are stabilized.
But before we can harvest there is a lot of work to be done. For example, the cutting starts around two years after planting the trees. Not in order to control the height of the tea plant, rather to promote the growth of side branches, and expand the picking surface in an early stage. Additionally, weeds can grow between the young tea plants. Therefore, often a vinyl sheet or straw is laid down to cover the ground and prevent weeds from growing.
Recent planted samidori seedling
SUNLIGHT OR NO SUNLIGHT
In Japan there are basically two methods of growing green tea, which differ in how much sunlight the leaves are exposed to.
Rotenen (tea plantations without covers)
Oishitaen (tea plantations with cover)
The amount of sunlight makes a mild tea with a lot of umami or a refreshing tea with slight astringency. Tea leaves contain a protein called L-Theanine, which creates the Umami taste.
This substance is created in the roots of the tea plant and travels to the leaves. Exposed to sunlight this substance turns in to Catechin which causes astringency.
The tea plants get full sunlight exposure, so the leaves grow under natural conditions. This kind of production is used to create for example Sencha, Bancha or Genmaicha Green Tea.
As the new buds start to appear around mid-April the tea plants are being covered with reed screens, straw or man-made fiber cloths to avoid direct sunlight. No direct sunlight means that the L-Theanine is prevented from turning into Catechin in the leaves, what gives the tea more of an Umami taste. This method is used to create Gyokuro, Tencha (Matcha) and Kabusecha.
There are basically two types of shading to make tea with the oishitaen method
With this method, normally premium Gyokuro and Tencha (Matcha) is made. This method is more time-consuming than the direct covering method but gives you the opportunity of adjusting the amount of sunlight reaching the leaves.
In the front traditional canopy covered tea fields and in the background cheesecloth canopy covered tea firlds
Traditional canopy covering:
This method uses natural materials and has its origins in protection young sprouted tea leaves from late frost. The use of natural materials has several benefits like the possibility for the tea plants to breathe due to an air- and wind-permeable construction.
Everything starts in spring, when new tea buds begin to sprout, the whole tea field is then covered with bamboo-reed blinds. With this first step around 60% to 70% of the sunlight is blocked. After this initial shading step, approximately 7 to 10 days later, the final part of shading takes place. A wealthy amount of firmly dried rice straw is dispersed on top of the bamboo-reed blinds. The tee plants are now almost in complete darkness, around 95-98% of the sunlight is blocked to inhibit almost all photosynthesis. After around an overall period of around 20 to 25 days, the leaves are then ready to be harvested and further processed.
Cheesecloth canopy covering
The traditional way of covering tea fields is rather labor intensive, what opens the door for more economical ways of shading the tea plants. One of these rather less labor-intensive ways of covering is the use of black cheesecloth made of synthetic fibers. The application of cheesecloth canopy is very similar to the traditional canopy covering using bamboo-reeds and straw. After the first leaves start to unfold a first layer of cheesecloth is used to block the sunlight. Then after a bit more than a week, the second layer of cheesecloth is used to block almost 100% of the sunlight, so the leaves can grow almost in the complete darkness for up to 20 to 25 days overall.
Tea plantation with direct covered tea plants for Kabusecha
When using this method, the cloth - usually a cheesecloth - is applied immediately on top of the plants. With this method manly Kabusecha is made as well as lower grade Gyokuro, Tencha and recently Sencha. The covering time, usually around 10 days, is not as long as with canopy shading, but can be extended to up to 20 days. This method is the least time consuming and most economical shading method contemporarily in use for the cultivation of tea. Usually Japanese tea farmers us a black plastic material for this type of shading. But there are also other materials in use which give other benefits such as increasing the temperature around the plants. The downside with this method is that because the cloth is directly applied on the leaves, the leaves can get damaged because the shading material can flap against the leaves in the wind. and in addition, the amount of sunlight cannot be adjusted with this shading method.
Overall, the traditional method of shading is almost exclusively used for premium Gyokuro and Tencha (Matcha), due to a better taste of tea and more labor-intensive application. The new approach of shading, using synthetic materials is used for high grade Gyokuro and Tencha (Matcha) to serve a wider market due the economic benefits.
Depending on the region in Japan and weather conditions, tea leaves are ready for harvest at a slightly different time every year. In Uji the tea harvest starts usually at the end of April with Sencha and is followed by Gyokuro and Tencha (Matcha). In Japan, depending on the region, the tea leaves are harvested up to four times a year. The first harvest of the year, usually called Shincha, is in terms of quality known as the best tea of the year. Shincha is often referred as first flush tea or “Ichibancha”. As can be assumed tea leaves were picked usually by hand and only after World War II in the period known as “Japanese economic miracle”, the first usage of machinery in the tea harvest took place. Until this time tea bushes didn’t require a special shape, the usage of machines made it necessary to form them for this sole purpose. Today most tea produced in Japan is made out machine trimmed tea leaves, but there is still a demand for hand-picked leaves. Usually the leaves picked by hand tend to have a much more mellow taste and are generally seen to give a smoother tea than machine trimmed leaves give. Hand-picked leaves are much more precious and are only used for superior tea.
Today, in Japan there are three main ways of harvesting the tea leaves. Which differ in the amount of the leaves which can be picked and the quality output of the leaves.
Tencha leaves are being picked by hand
Handpicked harvest (1-3 kg/h)
The leaves are picked according to three different methods. The output, compared to other methods, is very small but the quality makes it worth it. From the time the sprouts start to appear to the time the leaves become too large to harvest, the tea leaves must be harvested as quickly as possible in one long stretch. Only with the use of skilled hands it is possible to pick a larger amount of leaves in the picking period which only lasts a few days. Tea picking usually takes place in the early morning until dawn and is performed by well experienced tea pickers. To pick a suitable amount of good sprouts a day, this long experience is required.
The best-known picking method is the “1 bud with 2 leaves” method: Leaves are picked from the tip of the stem to the first pair of leaves. Only the finest quality tea is made with this method.
Unlike the traditional picking method, automated harvest requires an even, oval shape of the tea fields. A machine has to cut the leaves at a certain height to be efficient. Therefore in spring, before the harvest, the fields are pruned to set the necessary height. Once the harvest has started the now newly appeared fresh buds, which have grown above this height, are now mowed to approximately the same height set in early spring.
Half-automated machine harvest on a Sencha tea
Half-automated machine harvest (300-400 kg/h)
Done with two people, the output is significantly higher than even using skilled hands for picking the leaves.
Half automated machine harvest takes place using a portable harvester. Two people are required to operate the machine efficiently and if possible, a third is required to hold the bag into which the tea leaves are collected. The downside is that the significant increase in efficiency comes with a lower quality of the harvested leaves. This method applies for higher grade green tea.
Tea plantation with direct covered tea plants for Kabusecha
Fully automated machine harvest (600-800 kg/h)
The most efficient way of harvesting tea leaves in Japan is the use of tractor harvest machine. The tractor is operated by only one person which rides on top of the machine and is steering and operating the machine during the process. The output is even greater than the usage of a half-automated machine but the machine depends on an even surface and tea fields specially arranged for this type of harvest. The machine is not operable on slopes or bumpy surfaces. It needs a maximal slope of not more than 15 degrees. Also the tea fields require a length of around 200 meters to provide a high efficiency.
Overall, the timing of the harvest is very important, because the harvest output and the quality are equally related to the harvest timing. Too early means a smaller amount and too late gives a bigger output, but the quality is going to be lower. Caffeine, catechin, amino acids (L-Theanine), which are the main components, gradually increase with the growth of shoots, but when the leaves grow bigger and start to harden, they rapidly decrease. Also, the crude fiber increases what leads to a poorer quality. Therefore, it is important to determine the time of harvesting the leaves to ensures a high output while maintaining good quality.
The area where usually a third and fourth harvests takes place is decreasing because of a too low price for such green tea on the market and the more prevalent demand for higher quality tea.
Tencha leaves in spring ready to be harvested
Freshly dried tencha leaves
Processing the leaves
From the time the tea leaves are harvested, they are exposed to oxygen what leads to an oxidation process. Oxidation is a process through which tea leaves are exposed to air in order to dry and darken. And just like fruits e.g. apples or bananas, when exposed to oxygen, tea leaves start to age, they turn brown and darken. Therefore, depending on the process applied, the same tea leaf can become green tea, oolong tea or black tea.
Generally speaking, different teas have levels of oxidation which in turn leads to different varieties of teas, including black tea, green tea, white tea and oolong tea. Where green tea is almost completely unoxidized tea, black tea is almost completely oxidized.
The key point in processing Japanese green tea is to stop the oxidation process as soon as possible after the leaves are picked. Tea processing in Japan can be divided in two processing steps.
This is the method of making sure that the tea can be properly sorted and flavor, color and fragrance can be extracted through brewing. Like in the past, the most important thing was to process the leaves so they can be preserved for a long time and give enough flavor when prepared. Simplified, for Sencha and Gyokuro this is usually done with steaming the leaves, rolling the leaves and drying the leaves at the end. For Matcha the leaves are steamed, dried and sorted according to size. At this point the leaves are called Aracha (荒茶): Aracha is roughly processed tea that has not gone through the final processing/finishing steps. This step is often done at the plantations and Aracha is then sold at tea auctions.
In this step, the goal is to improve the quality of the tea (currently Aracha). This step is applied for most teas in Japan to meet the demand for certain tastes and appearances. It can involve such steps as sorting, cutting, or blending. Sorting is to separate various tea particles (tea leaves, stems, or dust) apart from each other. Cutting can be used to create a uniform appearance of tea by making sure all tea leaves are the same in size. Blending helps to adjust tea flavor or tea price by mixing various tea sources together. Firing can add some pleasant light roasting notes to the flavor and aroma of green tea. It also helps to reduce moisture content even more.
Matcha is being groundes by using a stone mill made of granit stone from Aichi Prefecture
Matcha is the powdered green tea used traditionally in the tea ceremony. The processing method is completely different form the Sencha/Gyokuro processing method. Like Sencha and Gyokuro at first the main goal is to stop the oxidation, therefore the leaves are first steamed. But because Matcha is consumed in powder form the leaves don’t have to be rolled. After the leaves have been steamed they are now dried on a rotating belt in a big furnace where they go through several levels of drying to get the moisture content under around 5%. Now the leaves are called Tencha-Aracha.
Next, the leaf stems and veins are sorted out by cutting the leaves into smaller pieces and are then separated with air jets and sorted according to size. Additional steps can include further drying steps and classification, where unnecessary stems and old leaves and tea dust is removed.
The final step is the grounding process where the leaves are ground with a millstone made out of granite into Matcha powder. The particle size is around 15μm to 30μm. Because the grounding process is very slow, there are only around 40g of Matcha produced with one millstone in one hour.
Lower grade Matcha can also be processed with other industrial methods, with a productivity of around 10kg per hour.
Also, 100kg of fresh leaves give you under 20kg of powder: the weight is reduced greatly during the processing.
Partly processed Sencha (Aracha), stems are seperated from the leaves by air jets
Back in the day, before the invention of Sencha 300 years ago, and Gyokuro 150 years ago, only Matcha like powder tea was consumed but this tea makes up only around 3% of the total tea production in Japan nowadays. Compared to Matcha, Sencha and Gyokuro are produced fundamentally differently.
The most important step is the steaming process, where the leaves are steamed with 100°C steam for 20-120 seconds depending on the type of the tea produced. The next step in processing the leaves is a cooling step followed by the famous rolling step which in fact is not a single step, but rather a sequence of several similar smaller steps. The leaves are roughly kneaded while being dried with hot air, next they are twisted and kneaded to even out the moisture in them. Following is again a kneading and drying step before the leaves are shaped under heat and pressure into thin needles while being dried. Basically, during the rolling process moisture is removed by pushing the inside moisture to the surface of tea leaves. By doing so, rolling also helps to break tea leaf cell walls, that is necessary for water to be able to extract tea components when tea leaves are brewed.
Lastly tea leaves for Sencha as well as for Gyokuro are then dried. Drying can take at least half an hour and helps to reduce tea leaf moisture to just around 5%. This ensures that tea can be stored and preserved and further processed. The tea is now called Sencha-Aracha or Gyokuro-Aracha.
From here on the Sencha and as well as the Gyokuro leaves go through the secondary processing, mentioned above, which usually includes sorting the leaves according to size cutting big leaves into smaller ones if necessary, also removing powdered leaves, to make a uniform look.