Understanding two teas that share the same leaf, but not the same journey
Tea is one of the world’s oldest and most widely enjoyed beverages, yet few people realise that green tea and black tea come from the same plant: Camellia sinensis. What sets them apart is not their origin, but the journey each leaf takes from the moment it is plucked to the moment it reaches your cup.
To understand the difference between green and black tea, you have to follow that journey, from the fields through to the factory, and the delicate chemistry that unfolds along the way.
Green and black tea sit at the heart of Assam’s rich tea tradition. If you’d like a deeper understanding of how Assam tea is grown, crafted and distinguished by its unique terroir, our Ultimate Guide to Assam Tea offers a comprehensive overview. In the meantime, please read on to understand what is the difference between green tea and black tea.
The Shared Beginning: A Single Leaf, Two Destinies
Both green and black tea begin in the same way: with the careful hand-picking of tender leaves and buds. On a typical morning in Assam, the gardens come alive with movement as skilled workers select only the freshest leaves; the top two leaves and the bud. At this early stage, there is no difference between a leaf destined to become green tea and one destined for black tea.
The distinction emerges only after the leaf is harvested, when the processing pathways diverge and shape two entirely different styles of tea.
How Processing Shapes the Tea
Once the leaves are harvested, the journey of green tea and black tea diverges almost immediately. Although both begin with the same tender shoots, the decisions made in the factory determine the final character of the tea.
As a brief overview, Black Tea follows the process of Withering - Rolling - Oxidation - Firing - Grading.
Green tea follows the process of Steaming - Rolling - Firing - Grading.
Black Tea: Allowing the Leaf to Transform
In black tea production, the freshly plucked leaves are first withered. This is a slow process of moisture reduction which softens the leaf and prepares it for shaping. Once pliable, the leaves are rolled, which breaks the leaf cells and exposes their natural enzymes to oxygen. This sets the stage for oxidation (or fermentation, which is the traditional name used in Assam for what the global tea industry refers to as oxidation).
During this crucial phase of oxidation, the leaves darken from green to deep copper, developing the bold, malty flavours that Assam black tea is known for. The process is then completed with firing, where heat stops oxidation and dries the leaf, locking in its strength and aroma before it is graded by size and appearance.
Green Tea: Preserving Freshness from the Start
Green tea takes a very different path. Instead of withering, the leaves are immediately steamed after picking. This quick, precise heat treatment prevents oxidation from occurring at all. By halting this natural reaction at the very beginning, the tea retains its green colour, vegetal aroma, and higher concentration of natural antioxidants.
Once steamed, the leaves are rolled, although not to trigger oxidation, but to shape the tea and release some of its delicate fragrance. Finally, a gentle firing step removes excess moisture, creating a tea that remains bright, clean and remarkably fresh, before it too is graded for quality.
The Role of Oxidation: Where the Paths Separate
If there is one element that defines the difference between green and black tea, it is oxidation; a natural chemical reaction that occurs when the tea leaf is exposed to oxygen.
Green Tea: Preserving Freshness by Stopping Oxidation
For green tea, the goal is simple: halt the enzymes responsible for oxidation to prevent oxidation from happening. This is done through gently steaming the leaf to ensure it retains:
- its natural green colour,
- its fresh, grassy and vegetal aromas,
- and its lighter, cleaner flavour.
The result is a tea that remains close to its natural, unaltered state; a reflection of the leaf’s original character rather than transformation through processing.
Black Tea: Allowing Full Oxidation to Develop Depth
Black tea, by contrast, undergoes full oxidation in order to trigger a rich enzymatic reaction that gradually turns the leaf dark copper or brown and transforms its flavour profile.
During oxidation, the leaf develops:
- deeper, maltier notes,
- a richer, more full-bodied flavour,
- and a strength and colour characteristic of Assam teas.
The process is deliberate, controlled and central to what makes Assam black tea so distinctive.
Heat and Timing: How Technique Shapes Flavour
Green Tea: Gentle Heat for a Softer, Cleaner Cup
Because green tea is never allowed to oxidise, it does not go through the intense firing stages used for black tea. After steaming, the leaves are lightly dried at a lower temperature. This locks in their natural aroma while preventing bitterness.
The careful timing required during steaming and drying is what gives premium green tea its:
- smooth finish,
- clarity of flavour,
- and lack of harshness.
When done properly, the tea remains balanced and refreshing, never grassy or overly sharp.
Black Tea: High Heat for Complexity
Black tea completes its oxidation before undergoing high-temperature firing, the final step that stabilises the tea and concentrates its flavour. This firing stage is responsible for the tea’s bold structure; the malty richness, amber colour and layered character that makes Assam black tea so recognisable.
Taste, Aroma and Body: What You Experience in the Cup
Green Tea: Freshness and Subtlety
Because it remains unoxidised, green tea carries a lighter, cleaner profile. You may notice notes such as:
- soft vegetal or herbaceous tones,
- gentle sweetness,
- a refreshing, almost silky finish.
The overall effect is uplifting and bright; a tea that feels close to the leaf itself.
Black Tea: Strength and Complexity
Black tea expresses warmth, depth and structure. In Assam, this often includes:
- malty richness,
- hints of honey or cocoa,
- a smooth but robust body,
- a deep amber colour.
It is a tea built on transformation; the leaf you taste is very different from the leaf that was picked.
Caffeine and Antioxidants: Less About Type, More About Processing
Green tea is often described as “higher in antioxidants” and “lower in caffeine,” but the truth is more nuanced.
Green tea naturally preserves more catechins, the antioxidants present in fresh leaves.
Black tea converts these catechins into theaflavins and thearubigins, which carry their own antioxidant qualities.
Caffeine varies depending on leaf grade, growing conditions and brewing strength; not simply tea type.
In simple terms: Green tea feels lighter and gentler. Black tea feels stronger and energising. But both offer meaningful benefits.
One Plant, Two Traditions
The beauty of green and black tea lies in their shared origin and divergent journeys. Both come from the same leaf. Both require skill and precision. But the choices made during processing, whether to protect the leaf from oxidation or embrace it, create two distinctly different experiences.
At Dehing Tea, this difference begins in the same gardens but takes shape through two carefully managed, traditional methods, both of which take place in our tea factory located right on our tea garden estate. Our Assam green tea reflects the freshness of the leaf. Our second-flush black tea expresses the richness of the region.
Understanding these differences ensures you are able to recognise two distinct tea types and appreciate how craftsmanship, environment and timing transform a single leaf into two remarkable cups.
For a deeper look at how Assam’s landscape and tea traditions shape every cup, explore our Ultimate Guide to Assam Tea.