Japanese-style iced coffee
Japanese-style iced coffee is a hot filter brewed directly over ice: the water missing from the brew is supplied by the melting ice cubes. The hot extraction is kept and the coffee is drunk cold right away.
How can you make cold coffee without waiting?
Start the scene or choose a stage. The animation simplifies the mechanism; what follows gives the details and the available references.
Ice cubes are weighed into the bottom of the carafe: part of the recipe's water is already there, in solid form. In one amateur's recipe, a little under half the mass of the drink is put in as ice; this is not a standard.
Read the stages without animation
- Ice firstIce cubes are weighed into the bottom of the carafe: part of the recipe's water is already there, in solid form. In one amateur's recipe, a little under half the mass of the drink is put in as ice; this is not a standard.
- A shorter filterAn ordinary filter is made on top, with the dose of coffee planned for the whole drink, ice included, pouring only the hot water that is missing. The extraction is hot, but the coffee that drips is more concentrated.
- The coffee falls on the iceEach hot trickle melts a little ice as it arrives: the drink cools and dilutes in the same motion. Some Japanese coffee makers spread the dripping coffee so that it does not always dig into the same ice cube.
- The balanceAt the end, a few half-melted ice cubes remain at the bottom: the drink arrives cold and at the target concentration. The size of the ice cubes changes the result.
- A cup of filter coffee, coldA lively filter coffee is drunk right away, served iced: the hot extraction keeps a higher titratable acidity and more furanic compounds than cold brew. Cold makes the aromas more discreet; the argument that aromas are locked in by the ice has no study behind it.
To remember: Japanese-style iced coffee is a more concentrated hot filter, cooled and diluted in one go by the melting ice: it keeps the acidity of a hot extraction.
In history: In 1922, Ukers gives the rule for iced coffee: make it stronger than usual; the filter poured directly over ice was tinkered together in the United States in 2004 by a professional trained in Japan.
Read the full article and its sources ↓History
Japan has drunk cold coffee almost since it has drunk coffee. In 1903, Murai Gensai's cooking serial novel, “Shokudōraku,” that is “the pleasure of eating well,” published in the daily Hōchi, gives the recipe for a cooled coffee: the coffee is made strong, with little water and two crushed eggshells, a cup of hot water, sugar, milk or condensed milk is added, then the whole is bottled in glass, hung in the well or set on ice (source 1). A Japanese magazine relays an even earlier mention, a “coffee with ice” on the menu of an ice cream parlor in Kanda in 1891, which could not be checked in the book by Ishii Kendō that reports it (source 2).
In the United States, in that same year of 1922 when Ukers notes that coffee advertising campaigns push iced coffee as a summer drink, his book gives the rule: make the coffee stronger than usual, and, if crushed ice is added, strong enough to offset the dilution (source 3). This is already the calculation of the method, but there the coffee cools before meeting the ice.
The motion of pouring the filter onto the ice itself, with Japanese coffee makers designed for the purpose, entered the American trade through a barista from North Carolina. Signing as PeterG on a forum in 2012, he says he discovered in Japan, in the 1990s, iced coffees that kept their aromas and acidity, was trained for a year by Mr. Hayashi, of the Hayashi coffee institute, then tinkered with the method in 2004 and christened it “Japanese iced coffee” out of gratitude (source 4). In the same thread, another participant finds the name misleading and prefers flash brew, the lightning brew (source 4).
The motion
The ice is weighed into the carafe, then an ordinary filter is made on top, pouring only the hot water that is missing: ice and hot water together make the volume of a normal cup. The hot coffee melts the ice as it falls, and the drink arrives cold and at the right concentration. Japanese coffee makers are built for this; one spreads the dripping coffee so that it does not always dig into the same ice cube, which limits dilution (source 4).
A participant in the same forum gives his recipe: he first aims for the concentration he likes cold, then puts a little under half the mass of the drink in as ice, and counts on a few half-melted ice cubes at the bottom of the carafe at the end (source 4). It is an amateur's recipe, not a standard.
The settings
- Grindthat of the filter, slightly finer when less water is poured, according to a forum participant (source 4)
- Dosethat of a filter for the total mass of the drink, ice included (source 4)
- Brew ratioa little under half the drink in the form of ice in an amateur's recipe (source 4)
- Temperaturehot filter water; the 1922 rule only says to make the coffee stronger (source 3)
- Timethat of the filter; cooling is immediate
- Pressurenot applicable: gravity, as for any filter
What it has going for it
- The drink is cold the moment it is made, without waiting hours like cold brew or letting it age in the refrigerator (source 4).
- The extraction remains that of a hot filter, which lets more acids through than cold water: the cup keeps the liveliness that cold brew softens (sources 5 and 6).
- The equipment is that of the filter, plus a carafe and ice cubes, as the tinkering of 2004 showed (source 4).
What is held against it
- Dilution is delicate: the ice must melt enough to cool without adding too much water, and the size of the ice cubes changes the result (source 4).
- It does not suit every coffee: a forum participant finds that the most aromatic ones turn flat (source 4).
- What gives the cup its liveliness also gives it its flaws: at equal concentration, hot extraction is more bitter and more sour than cold extraction (source 7).
What it gives in the cup
No study read directly measures what ice does to the aromas of a hot filter; what follows is deduced from comparisons between hot and cold brews. Japanese-style iced coffee is a hot extraction: it has the higher titratable acidity (source 5), the more abundant furanic compounds (source 6) and, at equal concentration, the more marked bitterness and sourness than cold brew, which is more floral (source 7).
The Philadelphia chemists, moreover, point out that their “cold-brewed coffee” must not be confused with iced coffee, hot coffee served over ice (source 8). Both drinks are cold in the glass, but not in the same family: one is a cooled filter, the other a slow immersion. Cold, finally, holds back aromas instead of releasing them: served iced, a coffee seems less expressive than hot, as the forum's amateurs also note (source 4).
Anecdotes
- In 1903, Murai Gensai's recipe clarifies the coffee with two crushed eggshells; in 1902, an American importer cited by Ukers was still advising eggs and shells for a coffee boiled ten minutes (sources 1 and 3).
The sources for this sheet
- Murai Gensai, “Shokudōraku,” autumn book, serial in the Hōchi shinbun, January to December 1903; text from Aozora Bunko, record 50686, after the Iwanami Bunko edition of 2005 · online · primary · reading: yes, in Japanese
- Precious.jp, “アイスコーヒーは日本生まれ？”, August 1, 2019, relaying Ishii Kendō, “Meiji jibutsu kigen” · online · press · reading: relay read; Ishii Kendō's book not read
- William H. Ukers, All About Coffee, New York, 1922, ch. XXVIII (campaigns of 1914-1915) and ch. XXXVI (iced coffee recipe, boiled coffee of 1902) · online · secondary
- Home-Barista.com, thread “How to Make Japanese Iced Coffee,” posts of June 2012, including PeterG's of June 8, 2012 · online · forum
- Niny Z. Rao and Megan Fuller, “Acidity and Antioxidant Activity of Cold Brew Coffee,” Scientific Reports, 8, 16030, 2018 · online · primary
- N. Córdoba et al., “Chemical and sensory evaluation of cold brew coffees using different roasting profiles and brewing methods,” Food Research International, 141, 110141, 2021 · online · primary · reading: article abstract
- M. E. Batali et al., “Sensory Analysis of Full Immersion Coffee: Cold Brew Is More Floral, and Less Bitter, Sour, and Rubbery Than Hot Brew,” Foods, 11 (16), 2440, 2022 · online · primary · reading: article abstract
- Megan Fuller and Niny Z. Rao, “The Effect of Time, Roasting Temperature, and Grind Size on Caffeine and Chlorogenic Acid Concentrations in Cold Brew Coffee,” Scientific Reports, 7, 17979, 2017 · online · primary