Rolling and Oxidation – How Black Tea is Processed
In our last blog we talked about the processing of green tea and learned about the importance of “fixing” tea leaves. This week we’ll be exploring black tea and why black tea leaves aren’t “fixed.” So, grab your favorite tea, make yourself a cuppa and settle in.
Green tea as well as black tea come from the Camillia sinensis tree. The plucked leaves are withered to remove excess water and to make the leaves soft and pliable. At this stage, leaves intended to be green tea would be “fixed” to maintain their color and flavor. With black tea, however, the opposite effect is desired. When the enzymes in tea leaves have contact with oxygen from the air, a chemical change occurs. The flavor changes as flavonoids develop and the leaves become brown. This process, called oxidation, is highly controlled as different timing and circumstances produce different flavors. Generally speaking, a slower oxidation produces a milder tea. But before the leaves can be oxidized, they must first be rolled.
Rolling tea leaves releases the enzymatic juices so they can react with oxygen. There are two major rolling methods employed in tea production today: the orthodox method and the Crush-Tear-Curl method (often abbreviated as CTC). For the orthodox method, the leaves are kept whole or mostly whole and therefore oxidize slowly. The leaves are rolled between two and four times either by hand or by machine. Then the leaves are left to oxidize either by laying out in a cool room or packed tightly into bamboo baskets. The bamboo baskets slow down the oxidizing process by reducing the tea’s contact with the air. Oxidation normally takes three or four hours.
The CTC method was invented in 1931 and changed the tea world forever. The process involves toothed rollers that break the tea leaves down and roll them into pellets. These pellets oxidize within the hour producing a strong, brisk flavor profile typically favored by the British. The smaller broken tea leaves brew more quickly than the whole leaves making CTC leaves ideal for tea bags as well. Because of this and the quicker production time, CTC processed teas have dominated the tea market. Today, 80-95% of all tea is CTC processed.
Whether the leaves were rolled gently via the orthodox method or macerated by a CTC machine, the oxidized leaves are dried and packaged for sale. If you’re interested in trying a black tea, let us recommend two black teas we carry here at MarketSpice. If you like a strong robust tea, the Chinese-grown Keemun boasts a rich flavor with faint chocolaty notes. On the lighter side, our standard Darjeeling blend is bright with a slight fruitiness. We recommend brewing for 3-4 minutes with boiling or close to boiling water. Enjoy!