Green tea, black tea, pu erh: one shrub, three processes

The difference between green tea and black tea does not come from the plant: both are made from the leaves of the same shrub, the tea plant, Camellia sinensis. Everything happens after picking. For a green tea, the leaf is heated very quickly to stop it oxidising. For a black tea, it is left to oxidise all the way. Pu erh, for its part, adds a step the other two do not have: a genuine fermentation, by micro-organisms.

Same leaf, three processes, three cups that have almost nothing in common.

One single shrub

Green tea, black tea, white tea, oolong, pu erh: all come from Camellia sinensis. There are two main varieties, the sinensis variety, with small leaves, and the assamica variety, with large leaves. It is the latter, grown in Yunnan, that pu erh is made from.

Anything that does not come from the tea plant is not tea, strictly speaking. Rooibos is a South African shrub, hibiscus a flower: they are steeped like tea, but they are herbal infusions. We have devoted an article to that other family: tisane, infusion, decoction.

What happens to a picked leaf

A fresh tea leaf contains enzymes which, in contact with the air, oxidise its compounds and turn it brown. It is the same phenomenon as with a cut apple left on the table.

The manufacturing process comes down to deciding what to do with that oxidation: stop it straight away, let it run its full course, or stop it and then bring something else into play. The rest, rolling, drying, follows from that first choice.

Green tea: stopping oxidation

Shortly after harvest, the leaves intended for green tea are heated. The heat destroys the enzymes and fixes the leaf in its vegetal state: this is what the Chinese call sha qing, literally "killing the green". The leaves are then rolled, and dried.

The heating method marks the cup. Most Chinese green teas are heated dry, in a wok or a drum, which often gives them toastier notes. Most Japanese green teas are steamed, which keeps a brighter colour and a more grassy taste.

Rolling, for its part, gives the shape. The Gunpowder in our Nuit de Marrakesh is rolled into small, tight pellets. Équinoxe green tea and Mojito green tea are made on a base of China Sencha, in leaves. The first adds apple, cinnamon, orange, almond, rose, clove and vanilla (allergen: almond, tree nut); the second, lemongrass, lemon, mint and calendula.

The consequence for brewing: a leaf that has stayed green does not take boiling water well. Our green teas steep at 70 to 80 °C, for 2 to 3 minutes. Above 80 °C, they release too many tannins and turn bitter.

Black tea: letting oxidation run its course

For black tea, the opposite is done. The leaves are first withered, that is, left to lose part of their water. Then they are rolled, firmly enough to break the cells and bring the enzymes into contact with the air. They then oxidise until they take on a coppery colour, before being dried.

This step is often called "fermentation". The word is misleading: it is the leaf's own enzymes that do the work, not micro-organisms. The correct term is oxidation.

A point of vocabulary: in Chinese, black tea is called hong cha, "red tea", after the colour of the cup rather than that of the dry leaves.

Sri Lanka, formerly Ceylon, is one of the great black tea countries. The island mainly grew coffee until a disease, coffee leaf rust, ravaged the plantations in the 1870s. Tea had begun to take root there in 1867, when James Taylor planted the first commercial tea bushes on the Loolecondera estate, near Kandy. Our Âme de Sri Lanka black tea starts from a Ceylon OP, for Orange Pekoe, a grade of whole, long leaves, combined with ginger, cinnamon, peppers, cardamom, nutmeg and vanilla. It steeps at 100 °C, for 3 to 5 minutes.

Pu erh: a true fermentation

Pu erh takes its name from Pu'er, an old tea-trading town in the Chinese province of Yunnan. Since 2008, China has reserved this name for teas produced in certain areas of that province.

Its production starts like that of a green tea: the leaves are heated, rolled, then dried in the sun. The result is a base tea called maocha. It is afterwards that everything changes: this tea undergoes a fermentation in the proper sense, carried out by micro-organisms, moulds in particular. That is why it is called post-fermented.

There are two routes. Raw pu erh (sheng) ferments slowly, through an ageing process that can last for years. Ripe pu erh (shou) goes through an accelerated, moistened and controlled pile fermentation, wo dui, developed in 1973 by the Kunming tea factory.

Our Pu Erh d'origine is an unflavoured post-fermented tea, with a dark, round cup and woody, earthy notes. It steeps at 100 °C for 4 to 5 minutes, after a 10-second rinse if you want a cleaner cup, and takes 3 to 4 successive infusions.

What changes in the cup

• Green tea: a clear, vegetal cup, sometimes toasty. Steeped at 70 to 80 °C, briefly.
• Black tea: a coppery, stronger cup that takes milk. Boiling water, 3 to 5 minutes.
• Pu erh: a dark, woody, earthy cup. Boiling water, and several infusions of the same leaves.

All three contain theine, which is the same molecule as caffeine, and their product pages say so. The exact settings, family by family, are gathered in our guide how to brew loose leaf tea.

Frequently asked questions

Is black tea a green tea that has been left to age?
No. Once heated, a green tea can no longer oxidise like a black tea: its enzymes have been destroyed. The choice is made shortly after picking.

Is pu erh a black tea?
No. Black tea is oxidised by its own enzymes; pu erh is fermented by micro-organisms, after a first stage close to that of green tea. They are two distinct families.

Why is green tea steeped at a lower temperature?
Because above 80 °C, it releases too many tannins and the cup turns bitter. Black tea and pu erh, on the other hand, need boiling water.

Is the earthy taste of pu erh a flaw?
No, it is its signature. If it seems too pronounced, rinse the leaves for 10 seconds in hot water before the first infusion.