Processing Japanese Green Teas

Processing Japanese Green Teas

Japanese methods of processing tea were, for a long time, inspired by Chinese practice, but today they are radically different, mainly because of state-of-the-art technologies and specific processing methods that were developed and refined over centuries.

For the production of green teas, the Japanese "fire" the leaf using steam. Also known as the "Uji method," this process preserves extremely fresh aromas with notes of the sea and herbaceous plants.
In order to maintain competitive pricing on the international market in the face of high labor costs Japanese growers have been quick to adopt technical advances.

To produce Japanese-style green tea, the leaves must first be turned into aracha, a raw product that is then sold at auction to companies who complete the processing. After picking, the tea must undergo three essential stages in order to become aracha: steaming, rolling and drying.



Picking is carried out with a machine equipped with scissors and an air compressor, which blows the leaves into a bag. Two workers operate this small cutter, which adapts to the shape of the hedge to ensure precision picking. Faster but less precise, the harvester used for gardens located on the plains can be handled by just one person. Once the leaves are picked, they are quickly sent to the factory for processing.


Usually, the freshly picked leaves are sent straight to the dehydration stage. However; some growers let them stand for a few hours.


The leaves are then heated with steam, a process that lasts 20 to 80 seconds. Steaming is extremely important, relative to the aromatic quality .of the tea. A short steaming period (20 to 40 seconds) produces a tea in the Asamushi style: leaves are larger, fewer are broken, and they have a full, light taste reminiscent of green vegetables. A long period of dehydration (40 to 80 seconds) produces a tea in the Fukamushi style: the leaves have been softened by the long dehydration, are more easily broken, are smaller and produce an intense flavor and a darker liquid. This is the style of tea that the Japanese prefer today.


After steaming, the leaves are cooled either by being blown through synthetic mesh tubes using air jets or by- being placed in large rotating cylinders. This step eliminates excess humidity that could damage the leaves.


The leaves then undergo a preliminary drying process at 210°F (100°C) for about 45 minutes in a rotating cylinder: After this, they spend 30 minutes in a similar machine, where the temperature is lowered from 175°F down to 105°F (80°C to 40°C).

The edges of the cylinder are made of rough bamboo, and during drying, mechanical arms mix the leaves constantly so they brush against the walls, The mixing action is a determining factor in the color of the tea and the release of tannins, which by the same token affects the taste (texture, astringency, etc.) of the tea using Japanese style tea cups.


Rolling, which lasts 20 to 30 minutes, softens the stems and releases the natural oils contained in the leaves.


The leaves are dried a second time for 20 to 40 minutes at 86°F (30°C), again in one of the cylinders, in order to reduce the humidity created by the rolling process and to stabilize the oils on the leaves. After this stage, roughly 13 percent of the water remains in the leaves.

Some processors use up to five or six different rotating cylinders throughout the processing, each of which has a different temperature and a different rotation time. The goal is to maintain the leaves at a constant temperature between 85 and 95°F (30 to 35 °C) and to reduce their moisture content gradually.


A machine equipped with mechanical arms gives the leaves a needle shape during a process that lasts between 40 and 60 minutes at temperatures varying from 158 to 248°F (70 to 120°C).


The loose leaves then circulate on a conveyor belt for about 30 minutes as they are heated to 185°F (85°C). It is this third drying that finally produces aracha.



At the final stage of processing, different batches of leaves are sometimes grouped together and blended.


Next dust and stems are separated from the leaves, and the leaves are then sorted into different size using sieves. The sifting is done mechanically by means of static rollers and mesh. The leaves can also be sifted electronically using several cameras equipped with optical scanners. Each leaf is scanned and, depending on its size and color, is separated from the others by a high-precision air jet.


The final drying stage varies depending of the type of tea and the taste required. The leaves are usually heated tp a temperature of about 1050F (40°C) to bring out the aromas. When the firing time is increased, the aroma of fresh grass diminishes and notes closer to those of grilled nuts are released. After the final; drying stage, 1 percent to 3 percent humidity remains in the leaves.