Matcha originated in the Sui Dynasty of China and flourished during the Tang and Song dynasties. Matcha entered Japan with the Tang envoy at the end of the 9th century and has continued to develop to this day, before returning to China in the late 20th century.
What is the definition of matcha today? In China, matcha refers to a micro powdered tea like product made from fresh tea leaves that have been steam (or hot air) killed and dried using covered cultivation as raw materials, and processed through grinding techniques. Looking at Japan again, the Japan Tea Industry Association, a non-profit foundation, defines matcha as a ground tea obtained by directly drying tea leaves grown under cover without kneading, and then grinding the ground tea leaves into powder using a stone mill, which is called matcha. Later, the Central Committee also referred to powdered tea obtained by other methods as matcha. Based on the standards of both China and Japan, it can be found that the definition of matcha mainly focuses on the covering cultivation in the planting process, the withering and drying in the initial production process, and the grinding process in the refining process.
_So, how does a tea leaf turn into matcha?
_How do these key processes affect the unique flavor of matcha?
_What are the differences between the production process of matcha and green tea?
Matcha has undergone continuous reform and innovation in its production process, manufacturing efficiency, and product quality, from the most traditional handmade production to mechanized processing and now entering the field of modern manufacturing. For easier understanding, let’s experience the birth process of a good matcha up close by examining a standardized production process that emerged earliest and lasted the longest in the matcha industry, and was most commonly used after matcha processing entered the mechanized mass production mode.
1.Tea plantation coverage: Cover with shade for about 20 days before harvesting to allow fresh leaves to produce more theanine
This is the most important key step in determining the flavor of matcha, and the picking season for matcha is mainly concentrated in the three seasons of spring, summer, and autumn. Taking the highest level of spring harvesting as an example, tea trees in Yucha Village sprout in February every year and grow to one bud and two three leaves in early April. Covering tea trees with shade nets or grass curtains to shield over 90% of ultraviolet radiation requires approximately 20 sunny days.
In a shaded environment, tea continues to grow, but the rate of lignification slows down. The content of chlorophyll and theanine in the leaves increases, while the content of tea polyphenols and caffeine decreases. These changes in content provide matcha with a high freshness and low bitterness, forming a natural fresh sweetness and seaweed aroma that is different from ordinary green tea. The leaf morphology is also greener, more tender, and larger than ordinary tea leaves.
2.Tea picking: manual or mechanical picking
The picking day has arrived, and according to the tea canopy formed by the closure of the garden in the autumn of last year, manual or mechanical picking can be chosen. Manual harvesting is used for non pruned tea gardens, while mechanical harvesting is implemented for pruned tea gardens. Manual hand picking is used to avoid cell breakage and ensure freshness. Insert new leaves from bottom to top until they naturally break. No fish leaves, old leaves, long green stems, and no foreign objects such as weeds, fallen leaves, or mesh mixed in. Fresh leaves should not fall to the ground to avoid the introduction of bacteria. Strictly perform canopy cleaning before machine harvesting to prevent foreign objects from entering the tea leaves, affecting the quality of dry tea, or causing food safety risks.
3.Green storage: Start the production line to collect green leaves and maintain the quality of fresh leaves
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 burning.
4.Steaming green: making tea taste fresher and greener in color
Steaming green tea is a crucial step that sets matcha apart from other green teas and is the oldest method of withering. Steaming green usually uses saturated water vapor, which utilizes the “latent heat” released by the liquefaction of water vapor to kill green. The heat transfer per unit time is much higher than that of general heat transfer methods, and can inactivate tea polyphenol oxidase in a short time (≤ 20 seconds), providing maximum protection for substances such as chlorophyll and amino acids in tea leaves. Compared to the traditional “stir frying” method of green tea, the steaming method of green tea leaves has a lower bitter taste, retains more fresh and sweet taste, and does not damage chlorophyll due to prolonged heating, resulting in a more vibrant green color.
5.Cooling: Tea leaves are repeatedly lifted and lowered in an 8-10 meter cooling net to remove moisture
The fresh leaves harvested from the steam engine have a large amount of steam condensate on their surface. At this time, the temperature of the condensate 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.
6.Drying: enter the furnace to dry, making the dried tea present a rich seaweed aroma and a lower bitter taste
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”. There are multiple layers of stainless steel conveyor belts inside the tea rolling furnace, and the blades move forward on the belts by exchanging layers with air. After passing through four different temperature belts, the initial drying is completed in 20-25 minutes.
7.Stem and leaf separation: After drying, the tea leaves are crushed, wind selected, and the stems, petioles, and veins are removed
After drying, the 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 during rotation. 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.
8.Secondary drying: Remove moisture from tea leaves to keep the moisture content below 5%
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.
9.Grinding and aging of matcha: The initial processed product of matcha, after 1-5 years of refrigeration and aging, has a richer flavor
After completing the above steps, the initial processed product of matcha is 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.
10.Grinding: Grinding tea into 1000 mesh ultrafine tea powder through processes such as stone grinding, ball milling, and air flow crushing
Grinding is the decisive step in why matcha is called “ground tea”. The oldest grinding equipment is stone grinding, which produces matcha with a special flavor. The surface of its particles presents more irregularity, which is very helpful in producing more foam when ordering tea. But the production efficiency of graphite is very low, generally each stone mill can only grind about 40 grams of matcha per hour. Powder processing technologies 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.
Thus, the production of matcha finished products is completed.
From the beginning of the dark journey, to the ultra-high temperature steam baptism, to the heavy impact of thousands of grinds and grinds, it took a full ten processes for matcha to present its unique and rich beautiful taste. With the development of technology, the planting, production, and processing techniques of matcha are constantly improving and innovating.