Oolong - semi oxidized tea
Partially oxidized teas are traditionally produced in south China and Taiwan. With over 3,000 types known, they have enjoyed hundreds of years of popularity. They are categorised by the percent of oxidation.
Oxidation is the core element influencing the taste and aroma of tea. The processing methods have different variants. Harvested leaves are sun withered, which slightly disrupts their structure. After a time of oxidation they are briefly heated and then dried at a lower temperature. The resulting drink is supposed to have a specific aroma and smoothness.
In Taiwan, tea has been grown since the 19th century. The Portuguese name for the island is Formosa, “Beautiful Island”.
The partially oxidized oolong type teas have become world renowned.
Top oolongs usually come from the January flush; then there is the first flush (end of April − May), second flush (end of May − June) and third flush (August).
It is probably the high price and limited quantity of the oolongs from Formosa that these teas are produced also in Darjeeling, India. The first attempts date to the 1980s, since when a number of plantations have joined the oolong club. Some of these teas are more than well done and they either imitate the Formosa oolongs or they have a specific, distinct taste. The production process is similar to the one used in Taiwan. The temperatures at which wilted tea leaves for oolongs are heated are significantly higher than those in black teas. It is a very sensitive process; although light caramel flavour is sometimes desirable and can be tolerated, overheating or burning should never occur.
Semi-oxidized tea and our health
Currently, about 400 different substances are known, which are contained in the tea leaf, are referred to as active substances. Tea leaf contains mainly: caffeine, polyphenols (tannins), flavanols, flavonoids, theophylline and theobromine (related to caffeine), fat, waxes, saponins, essential oils, carotene, vitamins C, B1, B2, B5, B10, B12, E. K, enzymes, iron compounds, K, F, Na, Ca, Cu, Ni, Zn, trace elements and many more.
Oolongs are partially oxidized teas and thanks to that a part of vitamins is preserved (full oxidation destroys vitamins) and beneficial minerals and tannins remain.
Tannins have an anti-inflammatory effect, soothe the stomach and intestines, heal the mucous membranes of the respiratory tract in colds. Theophylline stimulates blood circulation and relieves muscle cramps. The formation of tooth decay is prevented by the fluorine present.
Polyphenols (tannins) are found in all real teas and cause their slightly bitter astringent taste and characteristic aroma. After ingestion, they are absorbed into various organs. They are excellent antioxidants.