Green Tea (Camellia sinensis L.)

Camellia sinensis (L.) Kuntze is a member of the Theaceae family. It is a plant usually in shrub form. In 1753, it was named Thea sinensis by Linnaeus. In 1887, O. Kuntze named the plant Camellia sinensis (L.) Kuntze, which has three taxa: C. sinensis var. sinensis is cold-resistant and grows in China, Japan, and the following regions: Iran and northern regions, high regions of India, C. sinensis var. sinensis, C. sinensis var. assamica, which grows in tropical regions, and C. sinensis var. assamica, which grows in the southwestern region of China.

The tea plant is an evergreen, perennial plant. In order for the shoots to form continuously in green tea during the shoot period, rain should be abundant and the temperature should be sufficient. It is generally recommended and desirable to use two leaves and one bud plucked from the shoot tip for tea production. This is because the amount of polyphenol decreases from young leaves to old leaves in the plant. This means that the characteristic substances affecting the quality of the leaf are collected in the young leaves and buds. The plant is evergreen in summer and winter. The leaves are simple, without stipules and in spiral arrangement. The flowers are mostly solitary, hermaphrodite, actinomorphic, large. The sepals are imbricate, with five or more petals that are free or united at the base. The stamens are very numerous and usually united at the base of the corolla. The ovary is superior, with three to five locules. The flowers are showy and solitary or two to three together. The sepals are five to seven, with seven to eight petals. The calyx has five to seven sepals. The corolla has seven to eight petals. The stamens are united at the base. The fruit has three eyes, each bearing one to two seeds.

C. sinensis (L.) Kuntze is cultivated in many tropical and subtropical climates, especially in China, and is grown in countries such as India, Sri Lanka, Japan, Indonesia, Pakistan, Turkey, Kenya, Malawi and Argentina. There are four main types of tea production worldwide. There are four main types of tea: fermented tea (black tea), unfermented tea (green tea), semi-fermented tea (oolong tea) and lightly fermented tea (white tea). Green tea is produced by processing the top bud and leaves of Camellia sinensis. Green tea is obtained from the dehydration of C. sinensis leaves. Green tea does not undergo oxidation, whereas black tea does. This results in the formation of multimeric polyphenols in black tea, which are absent in green tea. Since no fermentation process is applied to green tea, the essential oil components present in black tea are not formed in green tea. It has been observed that black tea flavour is formed during the drying process.

There are two main methods of green tea production in the world. One of these is Japanese green tea production and the other is Chinese green tea production. In Japanese green tea production, the steaming process is applied. In Chinese green tea production, the dry hot air shocking process (pan-firing) is applied. The flavour of pan-fired teas is more intense and roasted than steamed teas.

The chemical content of C. sinensis has generally been investigated for the active ingredients in the buds and leaves of the plant. The upper two and a half leaves are the most valuable part of the plant and are therefore preferred in quality tea production.

Content in general;

• Purine alkaloids (methylxanthines): caffeine (2.9-4.2%), theobromine (0.15-0.2%), theophylline (0.02-0.04%)
• Triterpene saponins
• Catechins
• Flavonoids: Quercetin, kemferol, myrcetin
• Caffeic acid derivatives: Chlorogenic acid, theogallin
• Inorganic ions: Fluoride, potassium, aluminium ions
• Essential oil compounds: Linalool

A study by Carvalho et al. investigated the secondary metabolites in a methanol extract prepared from green tea using the high-pressure liquid chromatography (HPLC) technique. Theophylline and caffeine were found in the extract. Its use in China dates back to 5000 years ago. Green tea is used in Traditional Chinese Medicine and Ayurvedic treatment as a stimulant, astringent and diuretic, in heart health, headaches and body aches, digestive problems and depression, for detoxification purposes, for its energising and life-prolonging properties. It is also used to regulate body temperature and blood sugar and in the regulation of mental functions.

In Indian medicine, tea preparations are used for diarrhoea, appetite suppression, dry mouth, migraine, cardiac pain, fever and fatigue.

In Chinese medicine, green tea is used in the treatment of migraine, nausea, malaria resulting in temporary diarrhoea and digestive problems. It is also used as a preventive against cancer.

A review of the literature reveals that tea is used in our country for a variety of purposes. It has been reported that green tea is used as an antidote in cases of alkaloid poisoning, as well as for its stomachic, strengthening, and urine-enhancing effects. Green tea has been reported to be used in the protection of dental health, lowering cholesterol, and gastrointestinal system diseases due to its therapeutic effect.

Green tea, which is used in allopathic treatment, is the first herbal remedy to be approved by the FDA due to its high levels of catechin and polyphenol E (Veregen). Polyphenol E has been found to be effective in the treatment of anogenital warts due to its antiviral, immunostimulant and antioxidant properties.