How Oolong Tea is Made! | How It's Made | Science Channel

Like most teas, oolong is made from the leaves of a flowering plant species called Camellia sinensis. Harvest time is during the plant's peak growing season, which in Thailand is from May to November. Workers hand-pick what's known as the flush, a grouping of two young leaves and a bud which grows out the top of the plant. At this time of year, the plant produces a new flush An experienced tea master directs every phase of the processing, the first step of which is called solar withering. Workers bring the leaves into a glass-roofed building, then spread them out in the sun for 15 to 20 minutes. This kick-starts the oxidation fermentation process, as the chlorophyll enzymes inside the wilting leaves start breaking down. At the same time, the moisture inside begins evaporating. Workers keep moving the leaves around to ensure a thorough exposure to the sun, then they gather up the leaves for step two, indoor withering. The leaves lie on bamboo trays for six to eight hours, where, gently stirred every two hours, they oxidize further. Step three, disruption. The leaves go into a rotating drum. As they tumble, they bruise and tear. This breaks down the cell structures, enabling oxygen to penetrate deep inside, greatly accelerating fermentation. This also releases the leaf juices, which helps draw out the taste of the tea. When the tea master determines the leaves have sufficiently oxidized, they stop the oxidation process by tumbling the leaves in a gas-heated dryer for 10 to 15 minutes. This fourth step of the process is called fixation, because it fixes the oxidation at the desired level, which can be anywhere from 8 to 85 percent, depending on the variety of oolong in production. This is the most critical part of the process, because it determines the tea's taste, aroma, and color. The next step forms the tea leaves into tiny pellets. First, workers shake the leaves on a sieve to filter out the dust-like particles. Then they bag the leaves in a cotton cloth and place them first in a kneading machine, then afterward in a rolling press. Kneading and rolling the bag twist the leaves inside into tiny pellets. Forming these pellet shapes intensifies the flavor of the tea, and when the tea is steeped in hot water, releases that flavor slowly. They repeat the sieving, kneading, and rolling cycle up to 35 times, until the tea master is satisfied with the result. Then, and only then, does the final step begin, firing. They transfer the tea to an oven, in which it undergoes three drying cycles of 20 minutes each, at a temperature of approximately 100 degrees Celsius. This dries the damp tea, reducing the moisture content to the target level of less than 5%. The firing also brings out the fragrance. The traditional way to brew oolong is in a clay teapot, using about two teaspoons of tea per cup. Ideally, the water should be 90 to 100 degrees Celsius. Steeping time is from 3 to 10 minutes, and you can brew the same leaves up to 5 times.