Gyokuro Koridashi: The Ice Brewing Method That Takes Two Hours and Is Completely Worth It
Koridashi is a method of brewing gyokuro using only ice placed directly on the dry leaves, with no water added at all. As the ice melts slowly, it extracts the amino acids, sweetness, and umami from the leaves at the absolute lowest possible temperature, producing a tiny volume of tea so concentrated and pure that it tastes like a completely different drink. The method yields roughly 30 to 40ml per session and requires roughly two hours (depending on room temperature). It is considered by many to be the best way to drink gyokuro, and it can be prepared overnight to sidestep the waiting entirely.
Behind The Leaves #32
Other methods tested:
What Koridashi Is and Why It Exists
Koridashi translates directly to "ice extraction." The concept is an extension of the same temperature logic that makes all gyokuro brewing work. Amino acids, specifically L-theanine and the compounds responsible for umami and sweetness, extract readily at cold temperatures. Bitterness and astringency extract at higher temperatures. The traditional hot brew at 50°C suppresses astringency. The cold brew with ice water pushes that further. Koridashi takes the principle to its absolute limit: instead of pouring even cold water over the leaves, you simply place ice directly on top of the dry leaves and wait for it to melt. There is no input temperature to manage. The extraction happens at near-zero degrees as the ice gradually releases water directly onto and through the leaves.
The result, in theory and confirmed in practice, is the purest possible extraction of gyokuro's best qualities with essentially zero astringency or bitterness.
The Setup and What to Expect
The recipe is remarkably simple: 8 grams of gyokuro leaves in a glass teapot, with approximately 110 grams of ice placed on top. No water. No temperature to calibrate. No timing beyond waiting for the ice to melt sufficiently. A glass teapot was used in this session to allow the process to be observed visually. Because a glass teapot typically lacks a built-in filter, a small sieve is useful for pouring.
The key patience test arrives quickly. After one full hour, the ice in this session was still largely intact, and every drop of water that had melted had been absorbed directly into the dry tea leaves. There was nothing to pour or drink yet. The leaves were drinking before the brewer could.
At the two-hour mark, some liquid had finally collected but the ice still had not fully melted. The session was concluded at this point out of practical necessity, yielding approximately 30 to 40ml of tea.
What You Get After the Wait
Even at two hours with ice not fully melted, the resulting tea produced a reaction that makes the patience feel justified. The aroma alone is striking: despite the cold extraction, the umami richness is detectable in the air before the first sip. The colour is a visibly thick, concentrated liquid.
On tasting, the defining characteristic is clarity. There is no astringency, no bitterness, and none of the warmth that even a low-temperature hot brew introduces. What remains is pure sweetness and umami in their most unobstructed form, with a particularly strong sweetness in the aftertaste that lingers distinctly. It genuinely tastes like a different drink from the same leaves brewed any other way. The tiny volume, after more than two hours of waiting, makes each sip feel almost absurdly precious.
Key Takeaways
- Koridashi extracts at the absolute lowest possible temperature. Ice placed directly on dry leaves melts gradually, releasing water near 0°C. This means only amino acids, sweetness, and umami extract, while astringency and bitterness are almost entirely excluded.
The yield is extremely small. Expect 30 to 40ml from 8 grams of leaves and roughly 110 grams of ice. This is not a casual cup of tea. It is a concentrated, almost ceremonial small sip.
The waiting time is the entire challenge. Depending on the room temperature, the ice takes well over two hours to melt completely. This is the main reason even committed gyokuro drinkers do not use this method regularly.
The taste is meaningfully different from every other brewing method. The sweetness, particularly in the aftertaste, reaches a level and purity that is not replicable by any faster or warmer extraction. People who say this is the best way to drink gyokuro have a reasonable case.
From Yuki, founder of Tealife:
One key observation is that even with ice not fully melted at the two-hour mark, the aroma alone confirmed something different was happening. Despite the cold, the umami fragrance was detectable in the air from the wet leaves before the first pour, which speaks to the concentration of what was being extracted.
In direct testing, the tea yielded was approximately 30 to 40ml after more than two hours. The volume itself, tiny and hard-won, added to the experience. The sweetness in the aftertaste was described as unlike anything achievable through other methods.
One key personal observation: this is a method Yuki does not use frequently precisely because the patience required is genuinely difficult. The honest acknowledgement that even an expert rarely uses the "best" method due to practical constraints is worth flagging to readers.
Q&A
What is koridashi gyokuro brewing?
Koridashi means ice extraction. You place ice cubes directly on dry gyokuro leaves and wait for the ice to melt slowly, extracting the tea at near-zero temperature. The result is a tiny volume, typically around 30 to 40ml, of extremely pure, sweet umami tea with essentially no astringency or bitterness.
How long does koridashi take?
Depending on the room temperature environment, it could take up to or longer than two hours for sufficient ice to melt. The exact time depends on ambient temperature.
Why does koridashi taste different from other gyokuro methods?
Because the extraction temperature is so close to zero, catechins, which produce bitterness and astringency, barely extract at all. What remains in the cup is almost entirely amino acids, producing a sweetness and umami clarity that is distinctly purer than even a cold-water or low-temperature hot brew.
About the author:
Yuki is the founder of Tealife, a Singapore-based Japanese tea company. He’s passionate about Japanese tea and spends his time testing, trying, and experimenting - then sharing what he learns through content to help people discover the depth of Japanese tea beyond just matcha.