Tea
Family Theaceae
Camellia sinensis (= Camellia thea, = Camellia theifera, = Thea sinensis, = Thea bohea, = Thea viridis), tea (C. sinensis 1), is a small evergreen tree, up to 15 m high, but under cultivation pruned down to 100-150 cm, with alternate, oval to lanceolate, acuminate leathery and glossy leaves, 3-30 cm long (C. sinensis 2). The flowers (C. sinensis 3) are solitary or in small axillary clusters, fragrant, 2.5-4 cm across, creamy white, with numerous stamens and a superior ovary. The fruit is a brownish-green capsule, 1.5-4 cm in diameter, containing 3-6 seeds.
Use
The young leaves (C. sinensis 4) contain polyphenols, caffeine, essential oils and tannins. The caffeine content in tea is higher (3-4%) than in coffee (1-1.5%), but as in brewing tea more water is used, a cup of tea contains less of it than a cup of coffee. After picking the top leaves, they are taken to the factory for processing. This includes withering and rolling (C. sinensis 10) and fermentation. During fermentation of the leaves, the polyphenols are oxidised into coloured products that determine aroma of the tea. After the fermentation the leaves are dried (C. sinensis 11) and have changed from green to blackish. Green tea is produced by heating the leaf at an early stage to prevent
fermentation.
The many varieties of teas can be divided into two groups:
1. Camellia sinensis var. sinensis, China teas, which are slow growing and giving rather low yields; and
2. Camellia sinensis var. assamica, Assam tea (C. sinensis 7), which are quick growing and better yielding.
Plucking starts when the plants are 4 years old, and is done every 1 or 2 weeks (C. sinensis 8, C. sinensis 9, C. sinensis 12). Four pounds of green shoots produce 1 pound of made tea.
Distribution
Tea is a native of Southeast Asia, where the leaves have been used as a beverage for probably 3000 years. The Mongols adopted the habit of drinking tea and brought it as an article of trade into Central Asia. It was first brought to Europe in the 16th century, but it took another two centuries before drinking tea became established.
Tea was introduced into Java in 1690, but commercial production started only in 1824 (C. sinensis 5). Extensive cultivation started in Sri Lanka from 1870; in 1890 the first cultivation in Malawi started, but commercial production of tea in East Africa (C. sinensis 6) started only in the 1920s. The first introduction of tea into Russia was in 1846, but successful cultivation in Georgia started only in 1895. Tea has also been introduced into the New World, and there are small cultivations in South America.
Yields vary greatly, from 500 to 2000 kg per ha, depending on conditions. The biggest producers are India, China and Sri Lanka. The biggest importer is the UK, taking about 50% of the world’s import. Here the consumption per head is about 5 kg per year. Other important countries include the US, Australia, Canada, South Africa, Egypt and the Netherlands.