Green tea

Green tea comes from the leaves and buds of the *Camellia sinensis* plant, but unlike oolong or black teas, it skips the withering and oxidation steps. It first appeared in China around the late 1st millennium BC, and over time, its cultivation and processing spread across East Asia. There are many types of green tea, each shaped by the specific *C. sinensis* variety, where it’s grown, how it’s tended, the processing method used, and when it’s harvested. Drinking green tea might slightly lower blood pressure and boost alertness, but it doesn’t offer proven health benefits. Too much green tea extract, however, can harm the liver, interfere with prescription drugs, and cause stomach upset.

**History** Legend traces tea drinking back to China’s mythical Emperor Shennong. A key historical work is *The Classic of Tea* (茶經), written by Lu Yu between 618 and 907 AD. Another important text, *The Book of Tea* (Kissa Yōjōki), was penned by Zen priest Eisai in 1211; it discusses how green tea affects five vital organs, describes the plant’s shape, flowers, and leaves, and offers guidance on growing and processing the leaves.

**Steeping, Brewing, and Serving** Brewing green tea typically uses about 2 grams of leaves per 100 mL of water (or roughly 1 teaspoon per 150 mL cup). Water temperature ranges from 61°C to 87°C, and steeping time from 30 seconds to three minutes. Lower-quality teas are often steeped hotter and longer, while higher-quality ones are steeped cooler and shorter, usually two to three times. Premium teas like gyokuro call for more leaves and multiple short steeps. Overheating or steeping too long releases excess tannins, making the brew bitter and astringent, no matter the leaf quality. Warming the pot beforehand and adding hot water gradually while drinking also affect the taste.

**Production** In 2013, global green tea production hit about 1.7 million tonnes, with predictions it would double by 2023. By 2015, China supplied 80% of the world’s green tea, with exports rising 9% annually to 325,000 tonnes that year. The US was the top importer of Chinese green tea in 2015, taking in 6,800 tonnes (up 10% from 2014), while Britain imported 1,900 tonnes (a 15% increase).

**Growing, Harvesting, and Processing** How green tea is grown and processed varies by the desired type, which helps retain polyphenols and volatile compounds that influence aroma and flavor. Plants are either sun-grown or shade-grown, pruned into rows to encourage regular shoot growth, and typically harvested three times a year: first flush in late April to early May, second from June to July, and third from late July to early August (sometimes a fourth harvest occurs). Spring’s first flush yields the best leaves and highest prices. After picking, processing can be artisanal (sun-drying, basket or charcoal firing, pan-firing) or modern (oven-drying, tumbling, steaming). The resulting crude tea, called *aracha*, is stored in 30- or 60-kilogram paper bags under low-humidity refrigeration at 0–5°C. It’s not yet refined; a final firing happens before blending, selection, and packaging. This re-firing throughout the year extends shelf life and improves flavor, with first-flush tea from May storing well until the next harvest. After re-drying, the tea is sifted and graded by size, then blended by tasters and packed for sale.

**Import of Radioactive Japanese Tea** On June 17, 2011, at Paris’s Charles de Gaulle airport, French authorities found 1,038 becquerels per kilogram of radioactive cesium in tea leaves from Shizuoka Prefecture, Japan—more than double the EU limit of 500 Bq/kg. France rejected the 162 kilograms of leaves. Shizuoka’s governor, Heita Kawakatsu, argued that steeping the leaves would dilute the radioactivity to about 10 Bq/kg, even if the leaves had 1,000 Bq/kg, a claim backed by local tests. Japanese Minister for Consumer Affairs and Food Safety Renhō noted on June 3, 2011, that *aracha* is sometimes sold as furikake and eaten directly, so inspecting tea leaves, including *aracha*, was important for consumer safety. In 2018, the US Food and Drug Administration updated its import status on Japanese products potentially contaminated by radionuclides.