Green Tea: From Ancient Roots to Modern Health

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Background

In 1992, the global tea market reached nearly 2.5 million tonnes of production. The bulk of this output comes from the subtropical belt of Asia—China, India, Sri Lanka, Japan, and Indonesia—while today 35 countries cultivate tea, with India, China and Sri Lanka dominating the scene.

Black tea remains the most widely produced variety, followed by oolong and jasmine. The key distinction between teas lies in their processing: green tea leaves are harvested and immediately steamed or dried to halt fermentation, whereas black tea is left to oxidize.

Originating in China as a medicinal herb, the first documented use of green tea dates back 4,000 years. By the third century CE, it had become a staple beverage, and the industry began to flourish. China now boasts hundreds of distinct green‑tea varieties. Other major producers include India, Indonesia, Korea, Nepal, Sri Lanka, Taiwan, and Vietnam.

Japan adopted green tea during the Nara period (710‑794 CE) when Buddhist monks returned from China with seeds. The monk Eisai planted the first tea garden in 1191, promoting cultivation across the country and highlighting the beverage’s health benefits.

Tea ceremony—known as sado or chanoyu—emerged in Japan in the eleventh century, tracing its roots to the Tang dynasty (618‑907 CE) in China. A ceremonial ritual involved grinding a brick of tea into powder, whisking it with hot water, and serving it in ceramic bowls.

One of the earliest public tea ceremonies took place in the camp of Toyotomi Hideyoshi, the preeminent warlord of the time, to calm his troops before a major battle. Hideyoshi’s sado master, Senno Rikyo, is credited with elevating tea from a simple drink to a disciplined practice of self‑realization. Today, the Urasenke School remains the most prominent chanoyu institution.

Rikyu formalized the contemporary chanoyu style in the latter half of the sixteenth century. The ceremony, rooted in Zen principles, seeks to purify the soul and foster unity with nature. Its essence is expressed through calmness, rusticity, and graceful precision, with etiquette designed to maximize the economy of movement.

For five centuries after its introduction to Japan, tea was consumed only in powdered form. The first conventional green‑tea processing method appeared in the mid‑sixteenth century. Prior to the Edo period (1600‑1868), tea consumption was reserved for the ruling elite; mass production in the twentieth century made it accessible to the general public.

Today, green‑tea cultivation in Japan focuses on the warmer southern regions, with roughly half of production centered in Shizuoka Prefecture. Uji—adjacent to Kyoto—is Japan’s historic tea heartland and continues to produce the finest Japanese teas. The country yields approximately 100,000 tonnes annually from 60,000 hectares of tea fields, and Japan produces exclusively green tea.

While traditional production was manual, modern Japanese factories now fully automate the process. The primary variety, sencha, accounts for 80 % of green‑tea output and is graded into high, medium, and low tiers based on leaf selection.

Sencha is made from the tender top two leaves and the first shoot for the higher grades, and from the third leaf for the lower grade. Immediately after picking, the leaves are steamed for about 30 seconds to lock in flavor, followed by drying, pressing, and rolling.

Gyokuro represents the pinnacle of quality; its leaves are grown under 90 % shade using bamboo blinds. Matcha is derived from similar shaded leaves and ground into powder for exclusive use in the tea ceremony. Bancha is a lower‑grade, coarse tea made from older leaves harvested after sencha or during summer, divided into large‑leaf and small‑leaf categories.

Houjicha is a wedge‑shaped tea produced from Bancha roasted at 302 °F (150 °C) to halt fermentation, yielding a light golden hue. Kamairicha originates from northern Kyushu; it is first roasted at 392‑572 °F (200‑300 °C) and then cooled at 212 °F (100 °C). Traditional green tea is served plain—without sugar, milk, or lemon—to preserve its authentic flavor and aroma.

Raw Materials

Green tea is crafted from the top two leaves and buds of Camellia sinensis, a member of the Theaceae family and Theales order. This order encompasses 40 genera of evergreen shrubs and trees. The genus Camellia includes 80 species native to East Asia. In addition to the leaves, aromatics such as jasmine, flowers, or fruit can be incorporated during drying to create specialty blends.

The tea plant originates between India and China. Three principal varietals—China, Assam, and Cambodia—along with numerous hybrids, dominate the industry. The China variety reaches up to 9 ft (2.7 m) tall and can thrive for over 100 years. Assam trees grow up to 60 ft (18.3 m) and have an economic life of 40 years with regular pruning and plucking. The Cambodia variety averages 16 ft (4.9 m) and naturally cross‑breeds with other varieties.

The Manufacturing Process

Cultivation and harvesting

• 1 A suitable climate for tea cultivation requires at least 45‑50 in (114.3‑127 cm) of annual rainfall. Tea soils must be acidic—ideally pH 5.4‑5.8—and can be grown up to 7,218 ft (2,200 m) above sea level, spanning latitudes from the equator to the 45th parallel. Plants are propagated via layer‑planting or seed from mature trees.
• 2 A yield of 1,500 lb (681 kg) per acre typically demands two workers per acre to hand‑pick shoots and maintain the field. Harvesting intervals range from five to ten days, depending on location. Regrowth periods vary with the harvesting system and climate, often falling between 70‑90 days.
• 3 In Japan, harvesting commences at the end of April. A bud and several leaves are collected from each plant. The first crop appears in April‑May, the second in June, the third in July, and the final in September. For gyokuro or matcha, plants receive a two‑week shade after the first bud in spring before picking. Leaves are then shipped to factories; if immediate processing isn’t possible, they’re stored in large bins kept cool by blowing air into the base.

Drying

• 4 Post‑harvest, leaves must be dried to prevent fermentation. In China, green teas are commonly pan‑fired in large woks over flame or electric heat, with constant stirring for even drying. Withering spreads leaves on bamboo or straw racks for sun or warm‑air drying, again requiring regular movement.
• 5 In Japan, steaming predominates. Prior to steaming, leaves are sorted and cleaned. Steaming duration determines the tea type: sencha typically steamed for 30‑90 seconds; fukamushi sencha for 90‑150 seconds, producing a flaky light yellowish‑green tea. Steaming occurs in bamboo trays over water or on conveyor machines, followed by cooling to remove residual moisture.

Shaping

• 6 Rolling or shaping is largely machine‑based worldwide. In China, high‑end leaves are hand‑rolled into various shapes—curly, twisted, pointed, round—to influence flavor release and appearance.
• 7 In Japan, a dedicated machine performs initial rolling and drying simultaneously, taking about 48 minutes. This process strengthens leaves for subsequent pressing and removes both surface and internal moisture via heated air at 93.2‑96.8 °F (34‑36 °C). Operators still manually verify leaf texture.
• 8 The first roll distributes moisture uniformly across each leaf. A secondary rolling step, performed at room temperature for 24 minutes, further evens moisture by pressing leaves under a rotating disk.
• 9 A subsequent machine transforms leaves into a round shape over ~40 minutes, ensuring consistent moisture content across all batches.
• 10 Finally, leaves are separated into small portions and pressed into tiny round or needle shapes over 40 minutes, completing a total process of roughly three hours—significantly faster than hand‑rolled methods that can take up to ten hours.

Final drying

• 12 In Japan, the final drying stage lasts about 30 minutes after the last rolling step, reducing moisture to 5 % or less. The partially processed tea, called aracha, is then shipped to wholesalers. Aracha varies in size and may still contain stems and dust.

Post‑processing

• 13 Upon arrival at wholesalers, aracha undergoes grading and cutting by particle size, shape, and cleanliness using mechanical sieves and cutting devices. Additional drying follows to develop aromatic flavor, after which blending, packing, and shipping to retail outlets complete the supply chain.

Quality Control

Quality hinges on the initial leaf selection and the preservation of its natural attributes—color, aroma, and texture—throughout manufacturing. In Japan, strict temperature control (93.2‑96.8 °F / 34‑36 °C) during rolling, drying, and storage ensures optimal conditions. Cool air circulates at the base of storage containers to offset heat generated by the leaves themselves.

The Japanese government subjects all exported tea to rigorous inspections. Standard samples, established at the season’s start, serve as benchmarks for leaf, stem, moisture, flavor, taste, and color assessment. Chemical analyses verify tannin, caffeine, vitamin, and mineral content. Only tea meeting these standards receives export clearance.

The Future

While green tea’s health benefits have long been recognized, contemporary research substantiates many of these claims. Studies demonstrate that catechins—chief among them epigallocatechin gallate (EGCG)—can inhibit cancer cell proliferation. A Japanese study found that residents of Shizuoka Prefecture’s tea‑producing regions had a markedly lower overall cancer mortality compared to other areas.

Animal experiments corroborate these findings, showing reduced tumor growth and suppression of nitrosamine formation—known carcinogens. Green tea catechins also lower blood cholesterol, mitigate hypertension, and exhibit antibacterial and antiviral properties, including activity against influenza viruses and certain drug‑resistant bacteria. Additional benefits include combating halitosis, regulating blood sugar, and preventing dental caries through fluoride, amino acids, and polysaccharides.

Beyond its role as a traditional beverage, green tea—and especially matcha—may evolve into a novel therapeutic agent in the twenty‑first century, offering preventive and adjunctive benefits for conditions ranging from cancer to viral infections such as HIV.