Oolong Tea: From Harvesting to Processing to Brewing

Oolong tea leaves are harvested throughout the year, making up a significant portion of specialty teas harvested later in the growing season. The tea master lets the leaves stay on the plants longer, which enables them to acquire chemicals that are absent during initial budding. The combination of these chemicals and the intricate production process results in the distinctive taste and fragrance of numerous oolong teas.

Processing

The tea processing begins with the plucking of the leaves, which are then subjected to a short period of withering in the sun for up to four hours. This process is repeated thrice and followed by a “sweating” stage, where the leaves are delicately tossed in a room with high humidity and maintained temperatures of 68°F–84°F (20°C–29°C). The tossing helps dry the leaves evenly and ruptures their cellular structure, allowing the atmospheric oxygen to mix with the leaves’ PPO enzyme, initiating the oxidation process.

Unlike black teas, oolong’s oxidation process is not uniform due to the absence of stress and pressure during rolling. During the sweating stage, the oxidation begins on the leaf’s surface, gradually working its way toward the center, creating a red ring around the leaf’s edge, which is a rare sight in modern oolongs. The modern tea processors accelerate the oxidation process using various techniques, resulting in uniform oxidation, and a lack of distinct red bands.

Once the sweating stage is complete, the leaves are cooled and shaped into either the traditional long curvy leaves or the contemporary “wrap curling” style, where the leaves are rolled into small beads with a tail. In the traditional style, the leaves are tossed until they are rolled enough, whereas in the contemporary style, the tea master wraps the leaves in a cloth and rolls them into their unique shape using a mold, which is typically associated with Fujian’s Tie Guan Yin.

Oxidation

Oxidation is a critical aspect of creating oolong tea, an art form that requires mastery. Oolongs are classified as partially oxidized teas, with the oxidation level ranging from 6-8% to over 85%, depending on the tea type. The tea master’s responsibility is to determine when to halt the oxidation process by examining the leaves’ shape and aroma. The oxidation process is stopped by exposing the leaves to temperatures ranging from 392°F to 500°F (200°C to 260°C), which destroys the PPO enzyme. The high temperatures make the leaves pliable, and this stage lasts only a few minutes. If the oxidation process is stopped too early or too late, the resulting tea will taste entirely different.

Following oxidation, many oolongs are roasted over charcoal, which imparts a masculine, roasted, tar-like flavor and increases their shelf life. However, heavily roasted leaves can develop a pungent char taste that requires up to a year of aging for the tea to taste better.

Da Hong Pao, a Chinese national treasure, is a famous tea whose legend is shrouded in fantasy. The story tells of nine dragons that once ravaged the area now called Wuyishan in the northern section of China’s Fujian Province. A god destroyed the dragons, turning their corpses into black rock cliffs to quash the chaos. The god planted tea bushes high on one of these cliffs to commemorate his heroic feat. A monk, who was hiding a monkey in his robe, discovered the bushes. Because monkeys cannot harm a tree’s spirit, the monk instructed his monkey to climb the cliff and pick the most tender leaves from the bushes.

In another version of the story, the monk served the divine tea to a sickly scholar who, after drinking it, was healed of his ailments. The scholar then traveled north and mastered the Imperial exams, earning an audience with the emperor. At the meeting, the scholar discovered that the emperor suffered from the same ailments and brewed the divine tea to heal him. The emperor asked the scholar to return every harvest with the leaves from the first picking of his newly discovered tea plants and gave him a large red cloth to protect the young leaves. Thus, the legend of Da Hong Pao, or big red robe, was born. The remaining trees that produce Da Hong Pao teas are protected by armed guards and can fetch thousands of dollars per ounce.

Drying and shaping

After the oxidation process is stopped, the leaves are dried. Nowadays, most oolong teas are dried in ovens in a single step. However, some high-quality oolongs, particularly WuYi oolongs, undergo multiple drying stages where each succeeding stage dries the leaves in gradually cooler temperatures. This gentle cooling process gives the tea a distinct toasty flavor, which is the trademark of WuYi oolongs.

The most superior oolongs are the WuYi oolongs, also known as rock oolongs, grown in the vicinity of Wuyishan in the northern part of Fujian Province. These teas are named after the majestic rock mountains where the plants thrive. Among the rock oolongs, Da Hong Pao (big red robe) is considered the king of them all. It has a rich history of myths and legends surrounding it. However, modern versions of Da Hong Pao tea are only an approximation of the original tea as it was more fully oxidized and underwent numerous dry roasting stages. Nowadays, very few iterations of Da Hong Pao undergo dry roasting, and they are generally less oxidized than the traditional version, resulting in a more floral aroma and flavor.

Other remarkable rock oolongs include Shui Jin Gui (golden water turtle), Tie Luo Han (iron arhat or iron warrior monk), and the extremely rare Bai Ji Guan (white cockscomb).

Taiwanese Oolong

Taiwan has been producing tea since the early 1700s and oolong tea for about 150 years. Today, the small islands of Taiwan supply about 20% of the world’s oolong teas, and the country can be divided into five growing regions: northern, midcentral, eastern, south-central, and high mountain. The midcentral region mostly produces teas from cultivars brought over from China’s Fujian Province. The most famous Taiwanese tea from this region is Dong Ding, which is closely related to many famous oolong teas in the northern section of Fujian province and has influenced reducing the oxidation levels and changing the taste and aroma profiles of many classic teas, especially Tie Guan Yin, in China over the last century.

China’s cultural revolution had a significant impact on the world’s tea market, and historically, Taiwanese oolongs couldn’t compete with mainland Chinese oolongs. However, when trade between the West and China essentially stopped in the 1900s, the oolong market was supported almost exclusively by farms in Taiwan, most of which produced teas only for the domestic Taiwanese market. Over the past 80 years, as tea drinkers were exposed primarily to Taiwanese oolongs, their palates adjusted, and the flavor profiles created from the oolongs grown and processed in Taiwan are now dictating how the mainland processes its oolongs. The most significant change over the past century has been that Chinese processors are oxidizing their oolong teas significantly less than they traditionally did to create a more gentle, floral, and aromatic tea.