How time and processing turn into flavours.
Time tells when growing and processing tea.
While all true tea is made from the Camilla Sinensis plant, the variety and difference among teas is created by the length of time leaves are oxidised (the browning of the tea leaves when exposed to oxygen) and how they are processed.
Tea Processing Steps
The following methods are generally followed to process all types of tea, despite the different flavours and aromas that can be noticed in the end product.
- Plucking: Tea leaves and buds and two young are picked from Camellia sinensis bushes typically twice a year during early spring and early summer or late spring. Picking is done by hand when a higher quality tea (such as White Tea) is needed, or where labour costs are not prohibitive.
- Wilting: The tea leaves will begin to wilt or wither soon after picking,. This step, in which the leaves are dried by the sun or air, removes excess water from the leaves and allows a very slight amount of oxidation. The leaves sometimes lose more than a quarter of their weight in water during this stage. This stage starts the break down of leaf proteins into free amino acids and increases the availability of caffeine, both of which change the taste of the tea.
- Leaf maceration: The teas are bruised or torn in order to promote oxidation. Traditionally this is done by tossing or tumbling in baskets, or more often these days with machinery. Bruising promotes oxidisation and releases some of the leaf juices, which may change the taste of the tea.
- Oxidation: For teas that require oxidation, such as black teas, the leaves are left on their own in a climate-controlled room where they turn progressively darker. Sometimes they are also stirred. Tannins are released or transformed during this process. Oxidation is important in the formation of many taste and aroma compounds, which give a tea its colour and strength.
- Fixation: This process moderately heats tea leaves to stop oxidisation and remove unwanted scents, without damaging the flavour of the tea. Traditionally, the tea leaves are panned in a wok or steamed.
- Rolling: The damp tea leaves are then rolled to be formed into wrinkled strips by hand or machine. The rolling action also encourages some of the sap, essential oils, and juices inside the leaves to ooze out, which further enhances the taste of the tea.The strips of tea can then be formed into other shapes, such as being rolled into spirals, kneaded and rolled into pellets, or tied into balls, cones and other elaborate shapes.
- Drying: Drying is done to “finish” the tea for sale. Baking is usually the most common method of drying tea. The drying of the tea produces many new flavour compounds particularly important in green teas.
- Curing: Some teas required additional aging or curing to reach their drinking potential. Flavoured teas are manufactured in this stage by spraying the tea with aromas and flavours or by storing them with their flavorants, such as flowers.