Tea

Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of Camellia sinensis, an evergreen shrub native to East Asia. After plain water, tea is the most widely consumed drink in the world.

Etymology

The words for tea worldwide fall into three broad groups: te, cha, and chai. The English word "tea" arrived in the 17th century via the Dutch, who acquired it from the Min Chinese pronunciation tê. "Cha" entered English in the 1590s via Portuguese traders using the Cantonese pronunciation. "Chai" originated from a northern Chinese pronunciation of cha and travelled overland to Central Asia and Persia.

Origin and History

Tea plants are native to East Asia, with the probable centre of origin near the source of the Irrawaddy River, spreading into southeast China, Indo-China, and Assam. The earliest known physical evidence of tea was discovered in 2016 in the mausoleum of Emperor Jing of Han in Xi'an, indicating tea was drunk by Han dynasty emperors as early as the second century BC. The first written reference to boiling tea appears in "The Contract for a Youth" written by Wang Bao in 59 BC.

Tea drinking became widely popular during the Chinese Tang dynasty (618–907 AD). Lu Yu's The Classic of Tea (8th century) is the earliest known treatise on tea. Portuguese priests and merchants introduced tea to Europe during the 16th century. It became fashionable among the British in the 17th century, who later established large-scale tea plantations in India and Sri Lanka.

Botany and Cultivation

Camellia sinensis is an evergreen plant that grows mainly in tropical and subtropical climates. Two principal varieties are used: C. sinensis var. sinensis (Chinese small-leaf type) and C. sinensis var. assamica (Assam large-leaf type). Plants require at least 1,200 mm of rainfall per year and prefer acidic soils. Only the top 25–50 mm of the mature plant—the buds and young leaves called "flushes"—are harvested.

Processing and Classification

Tea is classified by its processing method, which determines the degree of oxidation:

• Green tea: Unwilted and unoxidized
• Yellow tea: Unwilted and unoxidized but allowed to yellow
• White tea: Wilted and unoxidized
• Oolong tea: Wilted, bruised, and partially oxidized
• Black tea: Wilted, sometimes crushed, and fully oxidized
• Post-fermented (Dark) tea: Green tea allowed to ferment/compost (e.g., Pu'er)

Chemical Composition

Caffeine makes up about 3% of tea's dry weight (30–90 mg per 250 ml cup). Tea also contains theobromine, theophylline, and polyphenols including flavonoids and catechins such as epigallocatechin gallate (EGCG). The astringency in tea is attributed to polyphenols, which constitute 30–40% of the leaves' composition.

Health Effects

There is no high-quality evidence showing that tea consumption provides significant health benefits beyond increased alertness due to caffeine. Black and green teas contain no essential nutrients in significant amounts except manganese.

Production

In 2022, global tea production was 29.8 million tonnes. The four largest producers were:

Global Consumption and Culture

Turkey has the highest per capita tea consumption in the world (2.5 kg per person per year). India is the largest tea-drinking nation by total volume. Tea is central to many cultural traditions, including the Japanese tea ceremony (matcha), Chinese Gongfu tea ceremony, British afternoon tea, Indian masala chai, and Moroccan mint tea. In the United States, approximately 80% of tea is consumed as iced tea.