The manufacturing method for Wuyi Yancha is very special and uses fine technology. It includes the essentials for making black and green teas. The manufacture includes proper selection of tea cultivar with optimum plucking, and at the same time, the application of very detailed heating (baking) technology. The degree of fermentation for Wuyi Yancha is more extensive than for Anxi Tieguanyin and Fenghuang Shuixian. It is a tea made with extensive withering and shaking. Except for the highest quality grade that still employs the
traditional manual processes, Wuyi Yancha is now mechanically processed using equipment such as withering trough, shaking machine, panning machine, rollers, and dryers. The manufacturing processes are simplified into withering, shaking, blanching, rolling, preliminary (primary) drying, and final drying (7).
a. Solar Withering Fresh tea leaf is evenly spread on withering trays with a loading density of 0.6-1 kg per square meter. These trays are loaded onto the withering shelves for solar withering. In order to have even withering, when the tea leaves are withered to a certain degree, they are gently piled and turned over manually without damaging the leaf. When the
sunlight is strong during noontime, it is not appropriate to wither the tea leaf under the sun. With tea leaf harvested on rainy days or in the evenings, traditionally it can be withered with heating indoor. With mechanical processing, tea leaf can be heat-withered in the withering trough. The time for solar withering depends on conditions of the tea leaf and weather condition. The time is shorter with stronger sunlight and longer with weaker sunlight. In general, it is within 2 hours. When a heated withering trough is employed, temperature is controlled between 32 and 38 °C for 40-70 min with depth of tea leaf between 15 and 18 cm.
Termination of solar withering is determined by a weight loss of 10-15% of the original weight of fresh tea leaf (i.e., the tea leaf retains about 65-70% of its moisture).
b. Indoor Sitting and Shaking This is a quality-determining step in the manufacture of Wuxi Yancha. Sitting and shaking are conducted alternately. During shaking, the tea leaf moisture evaporates gradually and softens the tea leaf, whereas during sitting, moisture in the leaf veins diffuses to the rest of the leaf and hardens the tea leaf. During sitting and shaking, the windows in the room have to be closed, maintaining a stable temperature between 22 and 27°C and a relative humidity of 80-85%. When room temperature is lower than 20°C, such as in spring with cool temperature and rainy days, supplemental heating is needed. Shaking causes the leaves to roll and turn over on the trays, allows the leaves themselves and leaf and tray surface to rub against each other, damages the cells in the leaf circumference, and induces partial oxidation and reddening. In general, the first shaking is conducted after sitting for 1 hour, followed by hourly shaking for 7-9 times.
In mechanical shaking, the shaker is 160-200 cm in length with a diameter of about 60 cm. It has a central axis. The body of the shaker is made of bamboo or wire mesh with a wooden or iron frame. Rotation is 10-25 times per minute. Each load weighs 10-12 kg. Shaking lasts 2-6 min for every 30-60 min, with a total of 8-12 shakings. Mechanical shaking is more efficient than manual operation and is more suitable for mass production.
Tea leaf that has undergone proper sitting and shaking has the following indicators: spoon-shaped leaf, with light green surface and bright reddish color circumference, leaf apex is prickly, ''sa-sa'' sound when turned over lightly, transparent veins, disappearance of greenish odor, light fragrant aroma, moisture content about 65%.
c. Panning and Rolling Traditional manufacturing process includes two panning and two rolling steps. Panning is conducted in a slanted pan with diameter of 60 cm and 25° slanting. Primary panning temperature is 180-220°C. Each load weighs 0.5-1.0 kg. After the tea leaf is loaded, it is turned rapidly with both hands. Panning lasts for 5-7 mins until the tealeaf is soft and sticky to the hands, with disappearance of greenish odor and appearance of pleasant aroma. After the primary panning, tea leaf is transferred to the roller for rolling when tea leaf is still hot. This primary rolling time is 2-3 mins. Leaf juice is leached out with the tea leaf rolled to a stringy shape. This tea leaf mass is broken up and again panned at 150-180°C. This secondary panning is basically a stewed panning until the tea leaf is too hot for the hands. The tea leaf is again rolled for a short time with pressure in order to tighten the stringy shape.
The mechanical process uses a blanching machine and rolling machine to conduct the panning and rolling processes, and the procedure is simplified to one panning and one rolling. Blanching can be conducted in either rolling-drum-type or pan-type blancher. The process should be conducted at high temperature, rapid and more stewed than ventilated panning. Rolling is generally conducted in a small rolling machine requiring high pressure, and rapid, hot rolling for 5-6 min. The tea leaf mass can then be disintegrated for drying.
d. Drying Wuyi Yancha is generally mechanically dried in a two-step process. The primary drying is at 120-130°C, with a loading density of 2 cm thick, and a final 70% dryness. The tea leaf is then spread to cool for 1-2 hr. The final drying is at 80-90 °C with a loading density of 3 cm thick until fully dried.
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