Tea 101

The Role of Oxidation in Teamaking

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One Plant, Two Lives

Every black tea. Every green tea. They all begin in the same place — with a leaf from Camellia sinensis. What happens next is everything.

From high in the hills of Darjeeling and Fujian to down in the Assam river valley, the same plant produces entirely different cups. The significance is not where it grows or who tends it, but the journey of oxidation that begins the moment the leaf is plucked.

Oxidation is a natural process where enzymes in the leaves interact with oxygen to convert polyphenols into complex flavor compounds. That may sound like a lot, but picture for a moment a green banana on a tree. When you pluck it, it starts to yellow, and brown and then blacken. Each step along the way, the banana smells, tastes, and feels different. Why? It changes through these simple enzymatic maneuvers of oxidation.

 green tea leaves on a white background

Green Tea

Shortly after plucking the leaf is heated – steamed, pan-fired or roasted – often within hours of harvest. This stops oxidation before it starts, locking in the green chlorophyll and grassy, vegetal brightness the leaf was born with, similar to a green or lightly yellow banana, if you will.

In the cup: Pale gold to jade. Fresh-cut grass, seaweed, sweet melon. Light-bodied and alive.

Tea cup with black tea leaves on a white background

Black Tea

Here the leaf is withered, rolled and left to oxidize, a full transformation, over many hours. When oxygen interacts with enzymes in the leaf it first turns copper, then deep brown, building malt and depth, much like a deeply browned banana perfect for banana bread.

In the cup: Deep amber to mahogany. Malt, dried fruit, warm spice. Full-bodied and grounding.

Tea being poured into a cup with a 'Smith' tea box on a green surface

“If only more people knew how important the alchemy of oxidation was in tea-making, perhaps they’d approach the cup in front of them with a sense of awe and wonder.”
-Donovan Eilert, Tea & Innovation

Controlling the oxidation is the craft. A carefully chosen moment to freeze-frame the leaf when it is at its peak. Green tea is kept bright and untamed. Black tea is allowed to grow mature and wise.

When we taste a new lot from Tumsong Estate or a spring flush from the hills above Hangzhou, the first question isn't always “where is this from?”, but rather, “how well was this natural evolution stewarded?”.

Bridging the gap from minimally oxidized and fully oxidized, you'll find Oolong, dancing between both worlds. But that's a story for another time.