Cold drip

History

The oldest description read is not Japanese but Cuban. Ukers, in 1922, recounts that in Cuba the coffee is ground fine, put in a flannel bag hung over a container, and cold water is poured over it, again and again, pouring the first drops back over the bag; a very concentrated extract is obtained, used to make café au lait or black coffee (source 1). The whole principle of today's towers is there: cold water passing through coffee, a slow extraction, a concentrate that is diluted afterward.

The names, for their part, promise an origin that no dated source read confirms. English says cold drip, Japan and Korea speak of Dutch coffee, the coffee world of Kyoto drip. Asked in 2024, the academy of the Japanese roaster UCC explains the Dutch name by Indonesia, a Dutch colony from the 17th to the 20th century, where very bitter coffees would have been extracted with cold water to make them drinkable; it says so itself in the conditional (source 2). Yet canephora, the only candidate for this bitterness, reaches Java only around 1900, after the rust (source 3): the story cannot explain a practice of earlier centuries.

Another story, widely repeated online, places the birth of the method in Kyoto, where tea would have been brewed with the cold water of the Kamo river before the process was applied to the coffee brought by the Dutch in the early 18th century; the post that tells it cites no source (source 4). The device is associated with Japan today, but no date, no inventor and no first printed mention of the glass tower have been found.

The chemistry, on the other hand, is recent and legible. In 2019, a Florence team compared cold immersion and cold drip for the first time (source 5); in 2021, a Bogota team measured what each one extracts (source 6).

The motion

The apparatus stacks three levels: at the top a reservoir of cold water, sometimes with ice cubes, fitted with a tap that sets the pace of the drops; in the middle a bed of ground coffee, often topped with a paper that spreads the water; at the bottom a carafe. The coffee is wetted first so that the first drops do not dig a channel, then the water is left to fall for hours.

Unlike immersion, the water arriving on the coffee is always fresh: the concentration gap between the bean and the liquid stays large, and it is this that drives extraction forward. Hence a higher yield than in immersion at the same temperature (source 6).

The settings

• Grindfine in the Cuban description of 1922 (source 1); not documented in the other sources read
• Dosenot documented in the sources read
• Brew rationot documented in the sources read; the product is a concentrate that is diluted (source 1)
• Temperaturecold water (source 1); 19 °C, to within 2 °C, in the Bogota tests (source 6)
• Timeseveral hours (source 5); drop rate not documented in the sources read
• Pressurenot applicable: gravity alone

What it has going for it

• Cold drip pulls more from the coffee than immersion at the same temperature: more dissolved solids and a better extraction yield in the Bogota measurements (source 6).
• You get a concentrate that serves for black coffee as well as for café au lait, as the Cubans described by Ukers already did (source 1).
• Like any cold extraction, it keeps a lower titratable acidity than hot brews of the same coffee (source 6).

What is held against it

• The cup comes out more bitter and more roasted than cold immersion of the same coffee, whatever the roast profile (source 6).
• The method is hard to reproduce: the Florence team finds large differences not only between the two cold methods but within each, depending on temperature and contact time (source 5).
• It depends on a fine setting, the drop rate, which the sources read do not quantify.

What it gives in the cup

In Bogota, cold drip coffee comes out the most loaded in the test, along with the coffee roasted fast and hot: the most dissolved solids, the best yield, the most caffeine, trigonelline and chlorogenic acids 4 and 5 (source 6). The panel finds it more bitter and more roasted, whatever the roast profile, whereas cold immersion and hot coffee stand out for sweetness, hazelnut, caramel and malt (source 6).

The authors link these soft notes, inversely, to caffeine, trigonelline, chlorogenic acids and dissolved solids: the more there are, the less the sweetness comes through (source 6). The bitterness of cold drip would therefore come first from the fact that it extracts more, and not from some mysterious virtue of the drop. The Florence team adds that bitterness, sweetness, sourness and overall intensity vary with temperature and contact time (source 5).

Anecdotes

The sources for this sheet

1. William H. Ukers, All About Coffee, New York, 1922, ch. XXXV (customs of Cuba) · online · secondary
2. UCC Coffee Academy, cited by Weathernews, “3つの抽出法で検証！水出しアイスコーヒーのおいしい淹れ方は？”, July 29, 2024 · online · manufacturer
3. PXL Roasters, plate “Canephora,” section “Java, 1900-1919: rust paves the way for robusta,” and its sources · secondary (page of the site)
4. Jake Tomszak, “Journal from Japan No. 2: Kyoto-style and the Origins of Cold Brew Coffee,” Coffee Ramble, January 26, 2025 · online · blog
5. G. Angeloni et al., “Characterization and comparison of cold brew and cold drip coffee extraction methods,” Journal of the Science of Food and Agriculture, 99 (1), 391-399, 2019 · online · primary · reading: article abstract
6. 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