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. Its origins trace back to China around the late 1st millennium BC, and cultivation later spread across East Asia. There are many types of green tea, shaped by the specific C. sinensis variety, where it’s grown, how it’s cultivated, the processing method, and when it’s harvested. While it might cause a slight drop in blood pressure and boost alertness, drinking green tea doesn’t produce health benefits.

History

However, taking too much green tea extract can harm the liver, interfere with prescription medications, and cause stomach upset. Legend says tea drinking began in China under the mythical Emperor Shennong. A key historical text is The Classic of Tea, written by Lu Yu between 618 and 907 AD. Another important work, The Book of Tea (or Kissa Yōjōki), was penned by the Zen priest Eisai in 1211; it discusses how green tea affects five vital organs, describes the plant’s shape and leaves, and explains growing and processing methods.

Steeping, brewing and serving

Brewing green tea typically uses 2 grams of leaves per 100 milliliters of water (roughly one teaspoon per 150-milliliter cup). Water temperature ranges from 61°C to 87°C, and steeping time varies from 30 seconds to three minutes. Lower-quality teas generally need hotter water and longer steeping, while higher-quality teas are steeped at cooler temperatures for shorter periods—often two or three times.

Premium teas like gyokuro require more leaves and multiple short steeps. If the water is too hot or the steeping too long, too many tannins are released, making the brew bitter and astringent regardless of leaf quality. Technique matters: warming the steeping container beforehand prevents rapid cooling, and leaving the leaves in the pot while gradually adding hot water during drinking also affects flavor. In 2013, global green tea production reached about 1.7 million tonnes, with predictions it would double by 2023.

Growing, harvesting and processing

By 2015, China supplied 80% of the world’s green tea, with exports rising 9% annually to 325,000 tonnes that year. The United States was the biggest importer of Chinese green tea in 2015 (6,800 tonnes, up 10% from 2014), followed by Britain (1,900 tonnes, up 15%). How green tea is grown and processed depends on the desired type, but the goal is to retain maximum polyphenols and volatile organic compounds, which affect aroma and taste. Plants are either sun-grown or shade-grown, pruned into rows to encourage regular shoot growth, and typically harvested three times a year: the first flush in late April to early May, the second from June to July, and the third from late July to early August (sometimes a fourth harvest occurs).

The spring first flush yields the best-quality leaves and commands higher 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. At this stage, it hasn’t been refined; a final firing happens before blending, selection, and packaging.

Import of radioactive Japanese tea

Leaves are re-fired throughout the year as needed, extending shelf life and improving flavor. First-flush tea from May can be stored this way until the next year’s harvest. After re-drying, the crude tea is sifted and graded by size, then blended according to tasters’ orders and packed for sale. On June 17, 2011, at Charles de Gaulle Airport in Paris, French authorities detected radioactive cesium at 1,038 becquerels per kilogram in tea leaves imported from Shizuoka Prefecture, Japan—more than double the European Union’s limit of 500 becquerels per kilogram.

France rejected the shipment, which totaled 162 kilograms. Shizuoka’s governor, Heita Kawakatsu, responded that drinking the tea posed no risk because steeping would dilute the radioactivity to about 10 becquerels per kilogram, even if the leaves contained 1,000 becquerels per kilogram—a claim backed by local tests. Japan’s Minister for Consumer Affairs and Food Safety, Renhō, stated on June 3, 2011, that because aracha is sometimes sold as furikake and eaten directly, inspecting tea leaves (including aracha) was important for consumer safety. In 2018, the U.S. Food and Drug Administration updated its guidance on the matter.