How Sencha is Made, Part 2: Aracha Production

Though the cultivation and harvesting of the tea leaves determines the quality of the raw material, the processing ultimately determines the final style, taste, and quality of the sencha.  If you haven’t read part one of the series where we look at sencha cultivation and harvesting, check it out here.

The post-harvest processing for most types of Japanese tea, sencha certainly included, can be split into to two main parts:

  1. The production of aracha (荒茶), also known as crude or unrefined tea
  2. Turning that aracha into shiagecha (仕上げ茶), also known as refined or finished tea

Sometimes a single producer will do both themselves, but it is generally more common for a farmer or farmers cooperative/collective to simply produce aracha which is then sold on the wholesale market to larger tea companies and producers for shiage (仕上げ - finishing)

Aracha Production

Aracha (荒茶) is the unrefined tea produced by the farmers or farmers cooperative/collective. As such, these processing facilities are generally located close to the tea fields so that the freshly harvested leaves can be processed as quickly as possible. Aracha is unrefined in that there are still unwanted stems, broken leaves, etc. in the tea which needs to be sorted out before the tea hits the consumer market. Additionally, aracha is generally blended with other aracha to produce a consistent blend

While it is possible for consumers to buy aracha on rare occasions, this tea is not designed to be sold directly, but is rather put on the market to be sold to wholesalers and refiners, who will sort, blend, and fire the tea to their and their customers’ tastes. 

The sencha aracha production process is relatively standardised across facilities throughout Japan, with the main variations being the style of some of the machines and the size of the production line. The production process for kabusecha and gyokuro aracha is essentially the same.

Before the mechanisation of Japanese tea production in the early 1900s, all tea was processed by hand. Today, handmade tea still exists in Japan, called temomicha (手揉み茶 - hand-rolled tea), though it is very rare and expensive. The machines used on the aracha production line are all based on the various steps and hand movements in the traditional temomi process.

Step Zero: Raw Leaves

Once harvested, the raw leaves must be transported to the aracha factory as quickly as possible before they begin to wilt and wither, in order to ensure freshness. Unlike Chinese green teas, most Japanese green teas are not withered before processing as withering produces strong floral aromas which are not desirable in a classic sencha. Recently, however, withered senchas are being produced and are called ichoucha (萎凋茶 - withered tea), ichou-sencha (萎凋煎茶 - withered sencha), or kaori-ryokucha (香緑茶 - aromatic green tea).

Commonly, the leaves are transported in cloth bags on kei trucks, which are weighed at the aracha facility to measure how much raw leaf was harvested. Then the bags of leaves are emptied into a bin which feeds a conveyer belt leading to the first step in the process. Warm humid air is blown through this bin to keep the fresh leaves from drying out too soon.

Step One: Steaming (蒸熱 - jōnetsu)


Steaming is used to prevent the leaves from oxidising, preserving their green colour, fresh aroma, and vegetal, savoury taste. While the vast majority of green teas around the world use dry heat (either by baking or pan-firing) to stop oxidation, almost all of Japanese green teas are steamed, which gives them their unique colour and flavour.

Oxidation is often confused with fermentation, which is a different process altogether that involves microbial activity and is responsible for the final two categories of tea: yellow tea and dark tea.

On the other hand, oxidation is the series of natural chemical processes by which the tea leaf slowly turns brown after being picked (in much the same way that an apple slice turns brown over time). During this process, the fresh, vegetal, and often savoury notes of green tea give way to the floral, fruity, and malty tastes and aromas of oolong and black teas. 

To stop oxidation from occurring, the heat from the steam deactivates the primary enzymes at work (such as polyphenol oxidase). This heating process, either using steam or dry heat (as in kamairicha or Chinese green teas) is often called ‘fixing’ or ‘kill-green’ in English, and is known as sassei (殺青) in Japanese.

There are two main types of steaming machine: conveyor belt and rotating drum. Both can be adjusted to shorten or lengthen the amount of time the leaves spend in the steamer, either by changing the belt speed or the angle of the rotating drum. 

Although there is no regulation regarding steaming time and specific times vary per region and producer, they are often roughy sorted in to into three categories as follows:

  • Asamushi (浅蒸し - light-steamed): <20 seconds
  • Chuumushi/futsumushi (中蒸し/普通蒸し - medium/normal-steamed): 20-60 seconds
  • Fukamushi (深蒸し - deep-steamed): >60 seconds

Generally speaking, higher quality leaves receive shorter steaming times to preserve the shape of the leaves and their fresh flavour. Deep-steaming is generally used on lower quality leaves to reduce astringency and to create a vibrant green colour.

As a result of longer steaming, the leaf becomes more moist and fragile, causing it to break apart during the subsequent rolling stages. The resulting tea is a mixture of a few intact needles, along with smaller broken pieces. This allows more pectin (soluble fiber) to dissolve when brewing, reducing the perceived astringency and increasing sweetness. Additionally, the broken leaves produce a cloudy infusion with a vibrant green colour, which has become a hallmark of the style.

Fukamushicha  or deep-steamed sencha was first developed in the 1950s as a way to revitalise the Japanese tea industry following WWII by making use of lower quality tea leaves grown in the flat lands of the Makinohara Plateau in Shizuoka. Compared to the leaves grown in the mountainous regions, this tea had a reputation of being bitter and astringent. Deep-steamed sencha eventually gained popularity in the 70s due to its ease of brewing, deep umami flavour, vibrant green colour, and lack of astringency. Since then it has become the most popular type of sencha in Japan today. However, due to issues with large-scale mass production and an overemphasis on greenness and umami, a lot of fukamushicha falls short of its promise, lacking character and aroma, and being overly bitter. Nonetheless, there are some smaller producers who continue to make amazing fukamushicha.

Step Two: Primary Drying and Rough Kneading (粗揉 - sojū)

After steaming, the goal of tea production is to dry the leaves evenly while maintaining a temperature that is neither too hot nor too cold, around 35C (95F) which preserves the tea’s aroma and colour.

Kneading the tea leaves brings the moisture from the inside of the leaf to the surface, ensuring it dries evenly. The moisture content of the leaves is expressed as a percentage of the weight of the dry matter in the leaves. For example, freshly picked leaves have a moisture content of around 400% meaning that ⅘ of the leaf is just water. When the moisture content is 100% it is half water, half dry material. 0% would be completely dry.

The machine used in this first drying/kneading process consists of a heated drum with a rotating central axis to which are affixed two types of arms. The first is a stirring arm which tosses the freshly steamed leaves through the hot air, allowing the surface moisture from steaming to evaporate. 

The tossed leaves fall to the bottom of the drum, where the second type of arm, a spring-loaded pressing arm, kneads them against a ridged surface, squeezing out moisture from the inside of the leaves. These leaves are then picked up again by the stirring arms, which toss them through the air, separating any clumps and drying them further.

Together, these two types of arms work together for around 40 minutes to dry and knead the leaves evenly until the moisture content reaches 100%. The skill of the tea producer is adjusting the speed of rotation, and the temperature and volume of hot air, in order to perfectly dry the leaves. If the drying happens faster than the kneading, the surface will dry out and the leaves will overheat and lose their freshness. If the kneading happens faster than the drying, the leaves will become mushy. 

In many factories, another machine will be used between steaming and this first drying/kneading step. This machine is similar in design, but only has the stirring arms and no pressing arms. The goal here is to further cool and dry the surface of the leaves straight after steaming.

Step Three: Rolling/Kneading (揉捻 - jūnen)

This next step is the only time during the aracha process in which heat is not applied, so little to no drying occurs.  Instead, the point here is to further equalise the moisture throughout the leaves. After the previous step, the blades of the leaves will have dried more than the stems and veins, so this extra moisture is squeezed out by applying pressure in a circular motion for 15-30 minutes. 

In this machine, the batch of leaves is placed in a cylinder with a weight placed on top. This cylinder then moves in a circular motion over a ridged plate. When everything is masterfully  adjusted to be just right, the machine does not knead the leaves at all, but rather makes the leaves knead each other, and cycle around ensuring even kneading.

Compared to the earlier rough kenading, the added pressure squeezes water (and tasty amino acids) out of the veins, petioles, and stems, and into the blades of the leaves. Not only does this make the tea dry more evenly, but it brings important umami flavour compounds to the surface, making them easier to extract when brewing. This process also begins to shape the leaves, making the final rolling easier.

Step Four: Intermediate Drying/Kneading (中揉み・中揉  - chūmomichūjū)

This two step process brings the moisture content of the leaves down to 32-35% and prepares the leaves for final rolling and shaping. 

This first machine in the process is very similar to the one used in primary drying and rough kneading (粗揉 - sojū) and is used to break up any clumps from the previous kneading step, while also drying the leaves and pressing them against a ridged surface to further knead them. After 10-15 minutes in this machine, the leaves are at about 75% moisture and are transferred to the next machine.

Though this next machine is also similar, there are a few key differences. Firstly, this drum also rotates, at roughly half the speed of the arms. This time there are no stirring arms, only pressing arms, which press the leaves against the ridged interior surface of the drum with 5-7kg of force. This process takes about 30-50min and lowers the moisture content to 32-35%. At this point, the leaves should be dry enough that they do not form a wet clump when squeezed in the hand, but rather crumble apart.

Step Five: Fine Rolling/Shaping (精揉 - seijū)

This last step is the most important in achieving the fine, needle like shape that sencha is known for. Here the leaves enter the most complicated machine, designed to mimic the skilled final shaping hand movements of temomicha masters. 

The leaves sit in a ridged, concave trough or pit, heated from below with propane gas to 50-60C (or 120C for machines working with larger batches). A weighted pressure plate rolls the leaves back and forth in a reciprocating motion while applying pressure. Leaves that spill out from this rolling trough are swept up by small rotating brush arms and returned to the trough. Like with the main kneading process, the leaves are mostly rolled against each other, rather than against the machine.


At first, the weight is light allowing the leaves to warm up and align themselves in the same direction. Then, after 2-3 minutes the weight is slowly increased, forcing the leaves to further align and tightly roll against each other. The leaves are kneaded at maximum pressure for about 10-15 minutes. 

How and when the weight is adjusted depends on the personal preferences and regional styles of the producers. For example, in the Kyoto area, the weight is increased slowly and rolling finishes under maximum pressure. However, in Kawane, Shizuoka, some producers like to increase the weight faster, but then back off the pressure for the last 10-20 minutes of rolling. 

At the end of fine rolling, the leaves have their needle-like shape, and have been reduced to around 13% moisture content.

Step Six: Drying 

Lastly, the shaped leaves are placed in a dryer to bring the moisture content down to 4-5%. Tea dryers come in either conveyor belt or shelf type styles. In either case, the leaves are spread in a thin layer, while hot air at around 75-80C is blown over them to dry them to the desired moisture content in around 20-40 minutes.

Why 4-5%? There are a few reasons. Firstly, anything over this could result in the leaves spoiling or molding. Under 4% can also cause the tea to deteriorate over the long term, so 5% is considered ideal for long-term storage. Also, 5% is the rule for the trade when selling tea on the market, as aracha (and tea in general) is sold by weight.


What’s next?

Despite this long and complicated (I’ve simplified things a tad) process, the tea is not ready for your kyusu. Classically, the aracha will be sold to another company who will keep it frozen until they decide to put the finishing touches (仕上げ - shiage) on it and produce whatever tea they desire. However, recently, there are more growers who do the shiage themselves. Check out part three where I’ll break down the general shiage process.






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