Japanese Iced Coffee: The Cold That Tells

Is it just a cold coffee?
No. It's one of the sleekest, most elegant, and underrated extraction methods in the specialty universe.
At TomassiCoffee, it’s not enough for us that something is trendy. It has to have a meaning, a technical balance, a voice.
Japanese Iced Coffee has it. And it speaks volumes.

Hot on Ice: An Opposing View

We are used to thinking that the cold requires slowness.
Cold brew is an example of this: a long, overnight, submerged infusion.
But Japanese Iced Coffee turns logic on its head.

It is extracted hot, with the same delicacy as a pour over, but directly on ice.
The heat opens the grain, releasing the volatile acids, the terpenes, the fruity aromas.
Ice freezes everything in its tracks, crystallizes the aromas, stops oxidation and returns a clear, vibrant coffee.

It's the balance between impulse and control.
Between the thermal expansion of the infusion and the crystalline retraction of the immediate cooling.

This is where certain profiles show new nuances.
A natural Ethiopia , perhaps from Sidama or Guji, with its floral and fruity notes, when hot extracted can be delicate, layered, deep.
But served cold, it gains a different sharpness.
The same notes stretch, light up, find space.
It's like listening to a familiar song in a different light: everything remains, but something resonates in a new way.

Technique and sensitivity: the two poles of extraction

Making a good Japanese Iced Coffee is not difficult. But it is delicate.
Because every detail, if unbalanced, has an immediate sensorial impact.

When hot water falls on ice, some of the final volume never makes it through the coffee bed.
That part, called the bypass, dilutes the drink.
If the coffee is under-extracted, that dilution accentuates the defects. If it is balanced, it highlights them.

For this reason we adopt a slightly finer grind than the classic tour-over.
A grain size between 650 and 750 microns, which increases resistance, retains liquid and brings the contact time into an ideal range.
So even if some of the final liquid comes from melted ice, the cup remains thoroughly extracted, clean and intense.

This principle is especially true with light-roasted coffees, which are rich in water-soluble but heat-labile aromatic compounds, such as fruity esters and volatile phenols.

A good example? The lots from central Kenya.
When poured over ice, something almost theatrical happens: the acidity, which can be sharp when hot, softens, leaving room in the case of our Kenia for notes of blackcurrant, pink grapefruit and toffee.

Our go-to recipe

Every coffee has its own voice, but this is the basic structure we use to get closer to the ideal extraction:

20 g of coffee ground between 650 and 750 microns
180 g of water at 94 °C
100 g of ice in the server
Pour-over method
Extraction time: about 2 and a half minutes

The final result is a drink of about 250 grams, with a balanced proportion between the extracted part and the diluted part.
The final temperature in the cup stabilizes between 14 and 18 degrees, depending on the environment and the type of glass used.

We start from here.
Then you listen to the coffee. You correct it. You refine it.

The trick is to work with raw materials that can support transparency.
Like certain micro-lots from Rwanda , where the Bourbon variety manages to generate a sweetness that remains suspended even in the cold.

Ice: silent protagonist of extraction

In Japanese Iced Coffee, ice is much more than a decorative element.
It is a control tool, a cold filter, a sensory mediator.

Its dissolution must be neither violent nor passive.
You need clear, compact, homogeneous ice, with a regular surface and high density.
Medium sized cubes, capable of melting slowly but cooling effectively.

The water it is produced with is equally important: filtered or minimally mineralized, with a TDS between 40 and 100 ppm.
Water that is too hard releases unwanted salts, alters the aromatic balance, and increases bitterness.
Water that is too pure, from total osmosis, reduces the buffering capacity of the ice and leads to a weak, loose, empty cup.

During the extraction time, the melted ice acts as an additional liquid part.
But after that, it is a guardian. It slows down the evaporation of aromas, preserves freshness, protects sweetness.

And when everything is in the right place, it only takes a few seconds to understand if you have chosen the right coffee.
The color, the visual density, the first sip.
Often a small hint of lavender or red fruit is enough to understand that you are in the hands of an origin like our Ngugu-Ini or Muhondo Honey .

Cold as a form of fire

At TomassiCoffee, we don’t treat Japanese Iced Coffee as a curiosity.
We treat it like a language. A lucid and precise way to tell what a well-roasted bean has to say.

We tested it on dozens of batches, adjusted grades and recipes, blind tasted, adjusted until we felt consistent.
And today, when we pour it, we put the same care into it that we put into preparing a competition set.

Because Japanese Iced Coffee, when made well, isn’t just cold.
It is the clearest form of heat.