Green Tea: How Processing Creates the Difference
Steamed leaf tastes marine and vegetal. Pan-fired leaf tastes nutty and toasted. One decision produces both.
All true tea comes from the same plant. What distinguishes green tea from black is that green tea is heated shortly after picking to deactivate the enzymes that would otherwise oxidise it. How that heating is done is the largest single determinant of the finished character.
Fixing
The heating step is called fixing or kill-green. It denatures polyphenol oxidase, the enzyme responsible for the browning that produces oolong and black tea. Two main methods dominate, divided broadly along national lines.
The two methods
- Steaming. Standard in Japan. Brief exposure to steam, typically 15 to 60 seconds.
- Pan-firing. Standard in China. Leaves tossed in a heated wok or drum.
- Steaming preserves chlorophyll and produces a deep green liquor with marine and vegetal notes.
- Pan-firing introduces Maillard reactions, giving nutty, toasted and chestnut characters.
Japanese Styles
| Tea | Distinguishing feature | Character |
|---|---|---|
| Sencha | Standard steaming, sun grown | Grassy, marine, brisk |
| Fukamushi sencha | Deep steamed, 60-120 seconds | Deeper, cloudier, sweeter, less astringent |
| Gyokuro | Shaded 3 weeks before picking | Intensely savoury, sweet, low astringency |
| Matcha | Shaded, stone ground | Whole leaf consumed; intense and thick |
| Bancha | Later harvest, larger leaves | Milder, less caffeine, everyday |
| Hojicha | Roasted bancha | Toasty, low caffeine, comforting |
| Genmaicha | Blended with roasted rice | Nutty, savoury, forgiving to brew |
Shading
Covering tea plants for two to four weeks before harvest reduces photosynthesis, which increases theanine and reduces catechins. The result is markedly sweeter and more savoury with far less astringency.
This is why gyokuro and matcha have their distinctive umami depth, and why they are brewed at unusually low temperatures — the compounds that make them special extract readily and the astringent ones are best left behind.
Gyokuro brewed at fifty degrees for two minutes is closer to a broth than to what most people think of as tea, and it is one of the great drinking experiences.Rasheeda Kamau
Chinese Styles
Chinese green tea is generally pan-fired, producing a paler liquor and a nuttier, sweeter, less marine profile. Regional styles vary enormously in leaf shape, which affects both appearance and extraction.
- Flat-pressed styles. Leaves pressed flat during firing; chestnut and orchid notes.
- Curled styles. Tightly rolled spirals of downy young leaf; delicate and floral.
- Pellet styles. Rolled into small pellets; robust, sometimes smoky, very long lasting.
- Needle styles. Straight, slender leaves; clean, sweet and vegetal.
Freshness
Green tea is the most perishable category. The compounds responsible for its fresh character degrade within months, and a green tea a year past harvest is a shadow of what it was.
This makes harvest date the most important thing on the packet. A tea sold without one, or with only a best-before date two years out, is telling you something about the seller's priorities.
- Buy green tea from the current year's harvest wherever possible.
- Japanese greens are typically picked in late April and May.
- Chinese spring greens are picked from late March through April.
- Store in an airtight container away from light, heat and odours.
- Refrigeration extends life for high-grade Japanese greens; seal thoroughly against moisture.
- Drink within six to twelve months of harvest.
Brewing Green Tea
The universal error is water that is too hot. Chinese greens want seventy-five to eighty-five degrees; Japanese greens want sixty-five to seventy-five; gyokuro wants fifty to sixty. Boiling water extracts bitterness and destroys the aromatics.
If green tea tastes bitter to you
Almost certainly the water was too hot, the steep too long, or the tea too old. Try a fresh, current-season tea at seventy-five degrees for ninety seconds. A great many people who believe they dislike green tea have simply never had it brewed properly.
The Second Infusion
Good green tea gives two or three infusions, each different. The second is frequently the best — the leaf has opened, the harshest compounds have already gone, and the sweetness comes forward. Discarding the leaf after one steep wastes most of what you bought.