What is fermentation in tea?
Tea is often described as either fermented, semi-fermented or not-fermented. The term when applied to tea refers to oxidation, not conversion of sugar to alcohol as in wine. Wine and beer are fermented through the addition of bacteria or yeast to grapes or hops. Tea fermentation occurs when the leaves are exposed to air. Fully fermented tea, such as black teas, are picked – then withered and rolled to fully expose the leaves to oxidation. Fermentation is controlled by adding heat, either through pan firing or steaming.
Fermentation, or oxidation, in green teas is minimized and controlled by applying heat to the leaves almost immediately after picking. This process seals in the grassy flavors and rich nutrients of the tea yielding a green and delicate brew.
Controlling the the fermentation process is a critical step in defining flavor and aroma of tea. Matcha tea is steamed immediately after picking, then air dried and deveined. The result is tencha – dried tea flakes, which are stored throughout the year until the next harvest. Tencha is ground into matcha powder in small batches, then sealed in air-tight packages. Your matcha tea should be date stamped for up to one year from date of packaging. Remember exposure to air, water, heat and light will diminish the flavor, aroma and hue of your tea, Keep matcha in air-tight, light tight canisters in a cool place.