Fermentation of Teas

Many types of tea come from the same plant, Camellia Sinensis. The different types of tea (e.g. Black tea, Green tea, Pouchong tea, Oolong tea) are the result of differences in the tea manufacturing process, and not due to different types of tea plants. However, from experience, tea manufacturers have discovered that certain varieties, locations, and seasons tend to produce Camellia Sinensis (tea plants), which produce better qualities of certain classes of tea.
One of the key steps in the tea manufacturing process, that is a factor in determining the type of tea that is produced, is the degree of fermentation the tea leaves are allowed to undergo. The term fermentation when applied to tea is something of a misnomer, as the term actually refers to how much a tea is allowed to undergo enzymatic oxidation by allowing the freshly picked tea leaves to dry. This enzymatic oxidation process may be stopped by either pan frying or steaming the leaves before they are completely dried out. One method of classifying teas are is based on the degree of fermentation: a) Non-fermented and Very Light Fermentation, b) Semi-fermented, c) Fully-fermented.
Non-fermented and Very Light Fermentation: These teas retain quite a bit of their original flavor. Green teas fall in this category. Most green teas like Dragon Well stop the fermentation process through pan frying while a few will stop the fermentation process through steaming. White teas undergo very light fermentation during the withering process. Sometimes these non-fermented and very light fermented teas will be scented with Jasmine petals to give the tea an aroma of Jasmine. Examples of Non-fermented and very light fermented teas: Green Tea, Dragonwell Green Tea, Pi Lo Chun, Steaming Green (Sencha), Jasmine scented Green tea, Yellow Tea, White Tea.
Semi-fermented: Tea which are allowed to undergo 10% to 80% fermentation fall into the broad category of semi-fermented teas. Tea brewed from semi-fermented tea leaves have a slight yellow to brown hue and possess a subtle fragrant aroma. These teas can be further classified into three categories based on their levels of fermentation:

Light (10% - 20%): Jasmine Tea (Pouchong scented with Jasmine petals), Pouchong Tea.

Medium (20% - 50%): Oolong, Tung-Ting Oolong, Ti-Kuan Yin, TenRen's King's Tea.

Heavy (50% - 80%): Champagne Oolong.

Fully-fermented: Black teas are fully fermented. Tea from Black tea leaves have a dark red hue and a sweet aroma of malt sugar. Example: Black Tea.

Post-fermented: Teas which are allowed to ferment and then have the processed stopped and later fermented again are known as post-fermented tea. Example: Pu-Erh Tea.

Non-fermented

Light-fermented

Medium-fermented

Fully-fermented