Oolong Tea explained

What is Tea?
All teas (white, green, yellow, oolong, black, pu-erh) come from the same plant, Camellia Sinensis. The Camellia Sinensis 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. Tea growing regions are largely in sub-tropical climate trekking along the Tropic of Cancer. 
There are multiple cultivars within the Camellia Sinensis plant. The two major varieties are Camellia sinensis var. assamica and Camellia sinensis var. sinensis. The Assamica varieties are larger in size and well suited for making black teas and pu-erh. The Sinensis varieties are smaller in size and are suitable for making all genres of teas except for pu-erh. Similar to wine, the different style of teas are distinguished by multiple variables: plant variety, growing condition (terroir) and processing methods that have been defined by culture and heritage.  
In Taiwan, Oolong tea as a genre represents 95% in both production and consumption. Within the tea industry, Taiwan is often described as the darling tea region that produce the best oolong teas in the world.

 

Identifying Oolong Tea
Oolong tea is commonly referred to as semi-oxidized tea or wu-long tea. Most oolong tea is grown in Taiwan and southeast China.   
Oxidation
Oolong tea is partially oxidized and has a wide range of oxidation levels, unlike green tea which is 0% oxidized and black tea which is 100% oxidized. Oolong tea oxidation levels can range from 8% to 85%, providing a large canvas for flavor variations and complexities. Lightly oxidized oolongs tend to be more similar to green tea, more vegetal but with hints of white flowers. Heavier oxidized oolongs tend to carry richer floral notes with maltier aroma similar to black teas.  
Roasting, also referred to as firing or baking
At the end of every harvest season, tea makers will make a decision on whether if they will be roasting that year's harvest. Roasting happens at the very end of the tea processing steps, where processed tea leaves are roasted via charcoal or electric oven for additional depth and aroma. 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.
 
Oolong Tea processing steps
Plucking                          
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.
    
Withering/Wilting        
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.

 

Maceration                   
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.
    
Oxidation                        
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.              
    
Fixation                           
Once desired oxidation is achieved, heat is applied to the tea buds in order to halt the enzymatic oxidation activities.
    
Rolling                             
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.
    
Drying                             
The drying process is applied to stabilize any remaining oxidation and to remove excess moisture.
    
Sifting/Picking               
Dried teas are then hand sifted, in order to weave out any undesirable elements such as large stems or unsuccessfully processed tea leaves. 
    
Baking                             
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.