Japanese Tea Processing

If you tried to taste a leaf just picked from a tea plant, you would realize that it doesn’t taste like tea. Harvested tea leaves need to be processed first to develop tea qualities we appreciate so much. In fact, depending on the process applied, the same tea leaf can become green tea, oolong tea, black tea, etc. Each tea category also has its own variations depending on production methods. In this section we will look at Japanese tea production and discuss processing methods for some of the most common Japanese teas.

Traditional versus Modern Japanese Tea Processing

It is important to mention that in Japan tea processing today differs heavily from tea processing a hundred years ago. Nowadays most of Japanese tea is processed in mechanized tea factories. Back in the day, though, it was all done by hand.

Tea used to be made on a traditional tea rolling table called hoiro. Hoiro normally had a firm surface, on top of which was a layer of Japanese paper – washi. Treated with persimmon juice it would become elastic and durable.

Hoiro also had an area inside for hot coal that was used to keep the body-temperature warmth on its surface. This low heat helped to slowly dry tea leaves as they went throughout the tea rolling process.

The efficiency of hand-rolling process was really low. Only about 4kg of fresh tea leaves could be processed at a time; and it needed about 5-6 hours of rolling by 2-3 tea farmers. Visiting Japanese tea factories today, it is hard to even imagine those times, but there are tea hand-rolling preservation societies that aim to preserve this method into the future.

Nowadays, Japanese tea is mostly processed by machines in tea factories. The function of a tea farmer/tea factory manager is mostly to adjust the setting and to carry out factory cleaning and maintenance works.

Primary and Secondary Japanese Tea Processing

Back in the day all the most important thing was to process tea leaves so that could be preserved for a long time and would give flavor when brewed. Through time Japanese tea processing got more and more elaborate. These days it can be divided into two: primary and secondary processing.

Primary processing, like in the old days, is to make sure that tea can be stored and that flavor can be extracted through brewing. In most cases primary processing involves steaming, rolling and drying. Steaming is used to stop oxidation. Rolling is used to release inner moisture of tea leaves by breaking their cell walls. Through rolling tea leaves are also shaped into the straight tea needles. Lastly drying is needed for reducing the moisture to the complete minimum, so that tea can be stored for a long time. In short, without primary process there would be no Japanese tea.

Secondary process, on the other hand, is mostly to improve tea qualities. It can involve such steps as sorting, cutting, blending, firing, etc. Sorting is to separate various tea particles (tea leaves, stems, dust, etc) away 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 roasted notes to the flavor and aroma of green tea. It also helps to reduce moisture content event more.

While tea can be consumed after the primary processing, most tea in the Japanese tea industry will go through the secondary process to meet the demand for certain taste and appearance.

Sencha Processing

Sencha is the most consumed Japanese tea today. Its production, however, started only about 300 years ago (before that it was common to have matcha-like powdered tea).

Sencha processing essentially has three key steps: steaming, rolling and drying. Steaming is the shortest but the most important step for Japanese green tea. It usually lasts anywhere between 30s-120s; and it helps to stop the oxidation inside the tea leaves.

Rolling step is the longest, as it takes several hours (usually around 3h). To be fair it is not a single step, but rather a sequence of several similar steps. Firstly, it starts lightly and helps to dry the extra moisture gained through steaming. Then it gets stronger and stronger to push 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. At the end of rolling, tea leaves are also shaped into beautiful straight needles.

Lastly tea leaves for sencha are dried. Drying can take at least half an hour or more, and it helps to reduce tea leaf moisture to just 5%. This ensures that tea can be stored and preserved.

From here on sencha would go through the secondary processing, described before, to improve its qualities and adjust its price.

Matcha Processing

Matcha is a powdered Japanese green tea, and the processing of it is totally different from sencha.

Like sencha it does go through steaming to stop oxidation. However, it does not have the rolling step. Rolling is not necessary, because eventually tea leaves will be ground to powder.

After steaming, extra moisture is dried by levitating the leaves in warm air corridors. From there they fall onto a rotating belt and are brought into a large furnace. In the furnace they go through several levels of drying to ensure that inner moisture is under 5%.

Because tea leaf stems and veins are often too tough to grind, especially when using a traditional stone-mill, they are usually separated from the leaves. Tea leaves may also be cut to smaller particles, so that they are easier to grind.

For matcha all the additional secondary processes to improve its qualities would be applied before grinding. In addition to sorting and cutting, it could include blending and firing.

Lastly dry tea leaves are ground to powder. Traditionally it was common to grind tea leaves by a stone-mill. That is a very slow process, and one stone-mill can only produce about 40g of matcha per hour. For lower grade cooking matcha, another industrial method is used, the productivity of which is about 10kg of matcha per hour. That is 250 times more compared to a stone-mill!

Hojicha Processing

Hojicha is a roasted Japanese tea. It is normally made from bancha, but sencha or kukicha could also be used. It goes through the regular Japanese green tea processing, as described in sencha processing section. At the end of it, it is roasted on high heat. Traditionally a special roasting pan – houroku was used. These days most hojicha is roasted in rotating drum machines with the heat source underneath. The heat is usually at 200°C and roasting takes at least 10min or longer.

Processing of Non-green Teas

Japan also make some non-green teas, such as oolong, black and fermented teas. Proportionally, however, together they make less than 5% of Japanese tea production.

In terms of oolong, it is mostly at experimental stage and currently there are no established standards for Japanese oolongs. Often tea leaves would be left to wither for some time, after which they would be rolled to induce some more oxidation. At the end they would go into drying that both helps to halt oxidation and reduces moisture in tea leaves.

If we talk about Japanese black tea, its processing totally differs from green tea too. For black tea steaming is not used at all; and instead harvested tea leaves are left to wither for 16h-17h. This naturally starts breaking tea leaf cell walls, exposing tea leaf components to oxygen in the air – hence the start of oxidation. Then tea leaves are rolled and bruised more to accelerate oxidation. Finally, they are dried to be able to store and preserve them.

The production of fermented teas differs depending of the kind of tea, so we will not expand here much. It suffices to say that fermented teas are steamed or boiled for varying amounts of time. They are then exposed to targeted bacteria and are left to ferment for several weeks or months. At last they are dried either in the sun or by using drying machines.

Final Words

It is fascinating, how all the different kinds of tea can be made from the same tea leaves – it all depends what processing method is applied. It is hard to think of another plant that is so generous and versatile as tea.