Black tea involves four main stages – withering, rolling, oxidation and drying. Leaves are air dried and withered for up to 18 hours, reducing water content and softening them for rolling, which can be done up to three times. This twists the leaves and as a result breaks the cells inside releasing natural chemicals and juices beginning the oxidation process. The leaf is then spread out in thin layers and left to oxidize for 20 to 30 minutes depending on the outside temperature. Finally, to ensure the leaves are evenly dried, they are fed hot air in temperatures of up to 120 °C.
Green tea is considered “un-oxidized” because there are no chemical changes during manufacturing, which involves slight withering, then steaming or pan firing, followed by a series of firing and rolling to shape and dry the leaf. Sometimes the leaves are hand rolled!
Yellow tea, a very rare and delicate tea, follows the same process as green tea with one extra step. The leaf is exposed to gentle heat and left to ‘ripen’, which kills enzymes. The leaf is then wrapped in a special paper while still warm and left to dry naturally for a few hours.
Oolong tea is a partially oxidized tea, which happens in one of two ways. To produce a brown leaf, it is sun withered and then dried on bamboo baskets indoors, which are turned every two hours and shaken to break cells. The leaves are then turned inside a hot panning machine for 5 to 10 minutes and then dried in hot ovens. The second option, yielding a much greener leaf, follows the same withering and tumbling process as the browner leaf, however, the leaves are put through the hot panning machine when they reaches a much lower oxidation level and are allowed to dry overnight. The next day the leaves are wrapped in large cloth bags of up to 9kg and rolled in a special machine to bruise the leaves, up to 60 times! It is then dried in large ovens.
Puerh teas are classified as either “raw” or “cooked”. Raw Puerh is withered and pan fired, rolled and kneaded, then sun or air-dried. The leaves are steamed and compressed into flat rectangular slabs or round cakes or left loose. These teas are then left to age for up to 50 years in a controlled environment, allowing a really slow oxidation process during this time. These can sell for thousands of dollars. The cooked method is basically a faster method of the raw. The leaves are covered for up to 40 days in a very hot and humid room after the initial withering and drying process, with regular uncovering and turning.
Any one of these teas can be flavoured or scented with spices, herbs, fruits or flowers. All of which are blended with the teas at the end of the manufacturing process. These must not be confused with herbal teas, which to make clear, are not part of the Camellia family. Herbal teas include Rooibos, Chamomile and Honeybush. The PC name, technically not including the word ‘tea’, is “infusion”, “herbal” or “tisane”. Make sure to check your packaging to make it clear whether there is actually “tea” mixed inside or just herbs, flowers, spices and fruit.