Green tea

Green tea is a beverage made from the leaves and buds of the Camellia sinensis plant.

It is distinct from oolong or black teas because it does not undergo withering or oxidation. This lack of oxidation preserves the green color and specific chemical profile of the leaves. People value green tea for its diverse aromas, flavors, and cultural importance. The variety of tea available depends on many factors. These include the specific Camellia sinensis variety, growing conditions, and horticultural methods. The time of harvest also plays a major role in the final product.

Growing and processing the tea involves several precise steps.

Tea plants are often grown in rows and pruned to produce regular shoots. Farmers typically harvest these plants three times per year. The first flush occurs from late April to early May and produces the highest quality leaves. The second harvest happens from June through July, while the third occurs in late July or early August. Some regions even see a fourth harvest. Once picked, leaves are processed using either artisanal or modern methods. Artisanal methods include sun-drying, charcoal firing, or pan-firing. Modern methods use steaming, tumbling, or oven-drying.

After initial processing, some teas are turned into a state called aracha.

This crude tea is stored in paper bags under low humidity refrigeration. The temperature for this storage is kept between 0 and 10 degrees Celsius. This process allows the tea to be re-fired throughout the year as needed. This technique helps extend the shelf-life and improve the flavor. Eventually, the tea is sifted, graded by size, and blended by professional tasters. Once blended, the tea is packaged and prepared for sale.

Making a cup of tea requires a process called steeping or brewing.

This involves combining tea leaves with hot water. The temperature for steeping usually ranges from 160 to 180 degrees Fahrenheit. Steeping times typically last between 30 seconds and three minutes. The quality of the tea often dictates the brewing method. Higher-quality teas, such as gyokuro, use more leaves and shorter steeping times. They can also be steeped multiple times. If the water is too hot or the time is too long, tannins are released. This makes the brew taste bitter and astringent.

The history of green tea stretches back thousands of years. It originated in China during the late 1st millennium BC. Legend says tea consumption began with the mythological Emperor Shennong.

Important historical texts have guided tea culture for centuries. Lu Yu wrote The Classic of Tea between 618 and 907 AD. Later, in 1211, the Zen priest Eisai wrote The Book of Tea. This text, known as Kissa Yōjōki, describes how tea affects five vital organs. It also provides details on the shapes of tea plants and how to process leaves.

Today, green tea is a massive global industry. In 2013, global production reached approximately 1.7 million tonnes. China is the dominant force, providing 80% of the world's green tea market in 2015. During that year, China exported 325,000 tonnes of tea. The United States was the largest importer of Chinese green tea in 2015, taking 6,800 tonnes. Britain also imported 1,900 tonnes that year. Interestingly, the Azores Islands in Portugal are one of the few European regions that support production.

Green tea contains various phytochemicals, including caffeine and polyphenols. These include compounds like epigallocatechin gallate (EGCG) and flavonoids such as quercetin.

While these components are studied for health, scientific evidence is often inconclusive. For example, research has not proven that tea prevents cancer or aids weight loss. Some studies suggest it may slightly lower blood pressure or cholesterol. However, excessive intake of green tea extracts can be dangerous. High doses of EGCG can lead to hepatotoxicity, which is liver damage. People taking certain medications, like the drug bortezomib, should avoid green tea. It is important to consume tea in moderate amounts to stay safe.