Matcha Production Technology

Matcha refers to a powdered tea product made from tea leaves cultivated under shade, which are steamed (or hot air-fried) and dried, then processed through a grinding technique. The Japan Tea Central Association defines matcha as: tea leaves grown under shade, dried without rolling, resulting in tencha, which is then ground into tea powder using a stone mill. Later, the association also referred to powdered tea produced by other methods as matcha. Typically, 6 pounds of fresh leaves yield 1 pound of tencha, and grinding 1 pound of tencha produces 0.85 pounds of matcha. On average, approximately 10 pounds of fresh leaves are required to produce 1 pound of finished matcha.

Matcha production process

Tea plantation coverage: is the most important key step in determining the flavor of matcha. Covering tea trees with shade nets or grass curtains to shield over 90% of ultraviolet radiation requires approximately 20 sunny days. The picking season of matcha is mainly concentrated in the three seasons of spring, summer, and autumn. It is harvested when it grows to about one bud and three leaves, with the highest grade in spring.

Green storage: Unlike green tea, matcha processing does not require withering, and fresh leaves can be processed on the production line. In principle, the fresher the tea leaves, the higher the quality of matcha produced. Provide sufficient storage space for green leaves, and store fresh leaves that have not been processed in a timely manner. The storage area for fresh leaves should be clean, hygienic, cool, odorless, well ventilated, and not exposed to direct sunlight. The storage thickness should not exceed 90 centimeters to maintain the freshness of fresh leaves and prevent them from spoiling.

Steaming: Saturated water vapor is usually used to kill tea leaves, utilizing the “latent heat” released by the liquefaction of water vapor. The amount of heat transferred per unit time is much higher than that of general heat transfer methods, which can inactivate tea polyphenol oxidase in a very short time (≤ 20 seconds), providing maximum protection for substances such as chlorophyll and amino acids in tea leaves.

Cooling: The surface of fresh leaves that have been killed by the steam engine contains a large amount of steam condensation water. At this time, the temperature of the condensation water is very high, which can easily stick the tea leaves together, causing them to clump together. The internal temperature of the tea clumps will continue to rise, directly affecting the color and quality of the matcha. Therefore, it is necessary to cool and dry the moisture on the surface of the tea leaves in a timely manner. The killed green leaves should be blown up and down multiple times in a cooling network of 8-10 meters by a fan to quickly cool and dehumidify. The cooling time should not exceed 30 seconds, until the moisture in the tea stem and leaves is redistributed, and the tea leaves are soft when pinched by hand.

Drying: Tea leaves that have been dried to remove surface moisture must be immediately placed in an oven for drying, resulting in a rich seaweed aroma and a lower bitterness. Traditionally, refractory brick furnaces are used for initial drying. The burning hot air first turns the cast iron pipes red to form far-infrared radiation, and then enters the hot air coil to dry the tea leaves one after another. This traditional heating method can give ground tea a unique “furnace aroma”.

Stem leaf separation: Dried tea leaves are separated using a stem leaf separator, which consists of a semi-circular metal mesh and a built-in spiral knife that peels off the leaves from the stem when rotating. The peeled tea leaves pass through a conveyor belt and enter a high-precision air separator to separate the leaves and stems, while removing impurities, leaving only finely divided and uniformly sized leaves.

Secondary drying: The leaves peeled off from the stem need to be further dried. The slender leaves enter a precision temperature controlled dryer for 20 to 40 minutes until the moisture content of the dried leaves is below 5%, which can further enhance their unique aroma.

Grinding and aging of tea: After completing the above steps, the initial processed product of matcha is called ground tea, which has a bright green color, uniform size, cleanliness, and prominent seaweed aroma. The ground tea will be stored in a cold storage at around 0 ℃ for 1-5 years to achieve aging. After a suitable period of refrigeration, the seaweed flavor of ground tea becomes more intense and the taste smoother.

Grinding: Powder processing techniques such as ball milling and air flow pulverization are more widely used for tea grinding. The grinding process needs to be kept at low temperature and away from light to protect the chlorophyll, theanine and other components of matcha from oxidation and decomposition. The particle size of matcha usually reaches 18 μ m (D60), which is around 800 mesh according to the national standard. Matcha is not necessarily the finer the quality, the better.