Green tea

Scientific name: Camellia sinensis leaves processed with minimal oxidation

1. Definition & overview

Green tea is a type of tea made from the leaves and buds of the tea plant Camellia sinensis, which have not undergone the withering and oxidation process used to make oolong or black teas.
It is one of the oldest and most widely consumed beverages in East Asia and beyond.
Because of the minimal oxidation, green tea retains a more “green” leaf colour and lighter flavour profile compared to more oxidised teas.

2. History

• Originated in China (late 1st millennium BC) and spread across East Asia, including Japan and Korea.

• Early texts such as The Classic of Tea by Lu Yu and Kissa Yōjōki by the monk Eisai describe green tea cultivation and consumption.

• Over time, various regions developed distinctive styles, cultivars, and processing methods — for example, Japanese steamed teas versus Chinese pan-fried teas.

3. Cultivation, processing & production

3.1 Growing

Growing conditions such as soil, climate, and cultivar affect the final flavour and chemical composition.
In Japan, shade-growing techniques (as used for gyokuro) elevate certain amino acids and yield a smoother, more umami-rich tea.

3.2 Processing

The key difference for green tea is that after harvest, the leaves undergo a “fixing” step — steaming or pan-firing — to inactivate the enzyme that would oxidise the leaves and turn them brown.

• Japanese style: usually steamed soon after plucking.

• Chinese style: often pan-fired, oven-dried, or hot-air treated, sometimes with more shape or twist.
  Because oxidation is prevented, green tea retains more of its original leaf colour and fresh vegetal or sea-weed/umami notes, rather than the roasted notes of more oxidised teas.

3.3 Production & global status

Green tea production is widespread, though China remains the major global producer.
It is described as minimally oxidized, non-fermented, and rich in catechins.

4. Varieties & flavour profiles

There are many varieties of green tea, differing by cultivar, growing region, harvest time, and processing style.
Typical flavour notes:

• Chinese greens: gentler vegetal taste, sometimes sweet or honeyed, with a light body.

• Japanese greens (such as sencha and gyokuro): deeper green colour, umami, and sea-weed notes with a more pronounced flavour.

• Other regional greens: newer producers outside China and Japan develop their own unique profiles.

  5. Brewing & serving

Proper brewing helps bring out the best flavour and avoid bitterness.

• Typical steeping: about 2 g of tea per 100 mL of water (around 1 teaspoon per 150 mL cup).

• Temperature and time: often between 61 °C–87 °C for 30 seconds to 3 minutes. Higher quality teas favour cooler water and shorter times, since overly hot or long brewing causes excessive bitterness.

• Pre-warming the vessel and making multiple infusions from the same leaves are common, especially for higher-grade teas.

  6. Chemical composition

Green tea contains water, caffeine, and various phytochemicals such as catechins and flavonoids.

• One cup is typically 99.9% water and very low in calories, with small amounts of vitamins and minerals.

• Catechins such as EGCG (epigallocatechin-3-gallate) are the main polyphenols present.

• These compounds are under active scientific research for their biological effects.

  7. Health effects & evidence

Green tea is often promoted for its potential health benefits, though the evidence varies.

7.1 Possible benefits

• Contains antioxidant compounds that may help protect cells from oxidative damage.

• Some studies suggest associations with improved brain function, fat metabolism, blood sugar management, and heart health.

• It may support cognitive function, fat burning, and longevity, though more research is needed.

  7.2 Limitations & caution

• Many claimed benefits are not strongly supported by human evidence.

• There is little reliable proof for cancer prevention, major weight loss, or cardiovascular protection.

• High doses, especially in supplement form, may cause liver toxicity and other side effects.

• Most studies are observational or small; randomized controlled trials show modest effects at best.

  7.3 Safe consumption suggestions

Moderate consumption of green tea is generally safe for most people.

• Limit intake to a few cups per day rather than very large volumes.

• Be cautious with supplements or concentrated extracts, as they may increase health risks.

• Consider caffeine sensitivity and possible interactions with medications.

  8. Cultural significance & use

Green tea holds deep cultural value in many Asian societies such as China, Japan, and Korea.
It plays an important role in tea ceremonies, hospitality, daily rituals, and is viewed as a symbol of purity and mindfulness.
Its flavour, processing traditions, and varieties reflect local culture and craftsmanship.

9. Storage & quality tips

To preserve freshness and flavour:

• Store green tea away from heat, light, moisture, and strong odours.

• Use high-quality loose leaf or well-sealed sachets; earlier harvests (spring flush) often produce a sweeter flavour.

• Brew with appropriate temperature and timing for the tea grade.

  10. Summary

Green tea is a minimally oxidised tea derived from Camellia sinensis, known for its fresh flavour, cultural heritage, and healthful compounds.
While it offers potential benefits, scientific evidence remains modest and sometimes inconclusive.
Enjoyed in moderation and prepared with care, green tea continues to be a beloved beverage among tea lovers worldwide.