Identifying Oolong Tea

Oolong tea is commonly referred to as semi-oxidized tea, wu-long tea, or blue-green tea. Most oolong tea is grown in Taiwan and south east China where their natural terroir is most suited for quality harvest. The oolong tea plant can thrive in a wide range of elevation, anywhere between 400 ~ 3,000 meters above sea level. The ideal temperature for growth is between 20~30 degrees Celsius and in 80%~90% humidity.

Aside from herbal tisanes such as pepper mint, rose, and chamomile, all teas (white, green, oolong, black, pu-erh) come from the same species, Camellia Sinensis. There are multiple cultivars within the Camellia Sinensis plant. Two major varieties are, C. sinensis var. assamica known for producing Assam black tea and C. sinensis var. sinensis popular in Taiwan and China often made into oolong teas. Teas are often distinguished by its natural terroir and plant varietals. Though the main differentiating factor is the complex artistry of tea processing. The two processing steps characteristically unique to oolong teas are the degrees of oxidation and the roasting duration and temperature.



Oolong tea is partially oxidized and has a wide range of oxidation levels, unlike green tea which is not oxidized and black tea which is 100% oxidized. Lightly oxidized oolongs tend to be refined in texture with vegetal sweetness while heavier degrees in oxidation result in more pungent floral aromas accompanied by mineral characteristics.  Oolong tea oxidation levels can range from 8% to 85%, providing a large canvas for flavor variations and complexities.



Roasting, also referred to as firing or baking

Near the end of processing, right before the loose tea leafs become finished product, the teas go through a unique roasting step. During this process, the twisted and tightly rolled dried leaves are roasted to layer on additional flavors. Higher roasting temperature or longer roasting time add notes of honeyed stone fruit and accents of smoky caramel. The roasting temperature typically varies depending on the style of teas, a key step that distinguishes the quality of the finished product.

Detailed Oolong tea processing steps are depicted below

Only tea buds are harvested for quality teas. High elevation tea gardens typically are harvested by hand due to the steep terrain. Machine harvesting is utilized, though only for low elevation gardens.
Young, freshly picked tea buds are spread out under the sun in bamboo mats to kick off the oxidation process while the moisture on the buds starts to evaporate.

The buds are brought indoors to a temperature controlled environment where they are hand tossed to bruise the edges of the tea leaves, allowing air to enter and soften the leaves.
Tea buds are then spread out on bamboo mats again, though this time indoors, where the heat controlled room accelerates its oxidation process until the desired levels are reached.              
Once desired oxidation is achieved, heat is applied to the tea buds in order to halt the enzymatic oxidation activities.
The heated teas are then rolled in small batches, by machine or by hand, to break the leaves fibrous structure so the tea juices can be released and stick to the leaf surface.
The drying process is applied to stabilize any remaining oxidation and to remove excess moisture.
Dried teas are then hand sifted, in order to weave out any undesirable elements such as large stems or unsuccessfully processed tea leaves. 
Last step of the process is baking or roasting, aimed to enhance and layer on additional aromas while extracting any remaining moisture before packaging for delivery.